Family Guy

Tonight's episode of Family Guy was a re-run from a few years back. If you were paying attention, you would have noticed the quick ham radio reference.

It's where Peter is Christmas shopping in the mall, Peter is watching TV though the window of a Bill's Ham Radio Hut.

More ham radio in popular adult cartoon shows

Happy Holidays!

Use it or lose it

The ARRL seems to only represent less than 0.2% (3.75 MHz of the total 24.165 GHz) of the total amateur spectrum.

About 40 years ago 2 meters and 70 cm were basically uncharted areas. Now they are populated. Undoubtedly the future of ham radio is in our huge - virtually unused microwave allocations. They have the necessary bandspace to support wideband modes.

The concept of a re-banding or significantly altering existing bandplans where established systems and modes are in place, would go over like a lead balloon. There would be so much unrest at just the mere suggestion that the ARRL membership would be in jeopardy, which is their pocket book.   

I've blogged before that the average ham is now in their 60's.  

And with age comes a love for tradition and to re-live the past, and cling to legacy modes for dear life. Retired, well-off folks are where the money is for the ARRL as well. So the league will cater to that 0.2 %, as that's where the bulk of their memberships and revenue are.

It would be great if the ARRL would pay more attention to operating practices on 50 MHz and above. Just about every month there is an article on CW in QST.. I don't think it's possible for that magazine to go a whole 6 months or a year without mentioning it. Instead I wish they would at least quarterly have an article from the technology task force. QST, the main magazine of the ARRL should put more emphasis on future technologies in my opinion.

*I stole the title from a piece that David, WA6NMF wrote in the TAPR PSR DCC 2007 issue, titled "Use It or Lose It, SHF Edition." He points out that companies are putting a lot of pressure on the FCC to allow unlicensed operations over a wider frequency range. There is much more amateur spectrum to lose if we don’t use it more actively. I highly recommend reading his piece.

HSMM can put our microwave frequency allocations to good use. These allocations (23cm-300GHz) make up 99% of hams total available frequency allocations. Yet, it's estimated that only 1% of hams are involved with any microwave operations.

D-Star <-> SIP Translation

One of the interesting things about D-Star is it's ability to route calls between radios by callsign. There are two types of calls with D-Star; directed calls and non-directed calls. Non-directed are much like we are all used to. A CQ type listening mode, where you basically hear all general CQ style traffic on the channel. In the directed call mode, you can ignore all this (think of it as call sign squelch), kind of do-not disturb mode, but either way you can be summoned by anyone making a directed call to you. The radios display the callsign of who you are talking to kind of like a caller id type of thing.

When systems are linked a gateway server tracks where various callsigns are coming from so that directed calls can route out to the appropriate radio end point as you mobile from city to city, etc.

The Session Initiation Protocol (SIP), works very similar. It has become a standard for VOIP and other text and multimedia sessions. The sip username/ secret can represent the D-Star callsign or device / radio endpoint. SIP usernames are usually represented numerically, as in extension 200, but they can also be alphanumeric. A meetme/ conference call/room can act like that big CQ style reflector that we are used to with IRLP and Echolink.

SIP devices can register dynamically with an Asterisk Sever The best example is a SIP based Wifi phone where you may travel from hotspot to hotspot, but the server keeps track of how to route calls back to you. Much like how a D-Star gateway can track and route calls to you.

In either example, D-Star or SIP, under each packets SIP data, the callsign or extension information, there is then the Real-time Transport Protocol (RTP) audio stream carrying ones voice. With D-Star this is AMBE encoded, and with SIP it's typically encoded U-law/G.711.

John, K7VE has a D-Star dream of convergence with SIP, an established real- world protocol using by VOIP networks.

To accomplish such an Asterisk/SIP to D-Star/AMBE bridge/translation, the patented D-Star codec would have to be decoded with a $20 hardware solution, such as the DV dongle developed by Moe Wheatley, AE4JY. It can then be transcoded to more common g.711 a-law/u-law codec.

He points out that once a channel driver is properly created the whole power of Asterisk can be brought to play as a D-Star radio can then be used like any other digital IP phone endpoint; conference bridges, interactive voice response, call out, autopatch, voice recognition, etc. Basically instead of an IP phone as a digital endpoint, we could use a D-Star radio.

Using the AMBE-2020 chips in a PCI card or USB dongle will allow the conversion of the DSTAR Digital Voice to/from alaw or ulaw 8k digital voice and the chip decodes/encodes DTMF ... this combined with the datastream (containing callsigns) should enable making DSTAR radios extensions on a Asterisk PBX (or even assign a DID to them) -- total 2-way ROIP/VOIP integration that can route to/through the PSTN. (Example: dial 1-800-4KB9MWR and get a call you can pick up on your DSTAR radio and vice-versa.) Pretty powerful for EMCOMM and personal use. All enabled by open source

http://www.mail-archive.com/dstar_digital@yahoogroups.com/msg02975.html

-Update May 1st, 2009-
Scott, KI4LKF announced today that he has written an asterisk channel driver (chan dstar) that can connect to D-STAR repeaters and reflectors.

Keep your eyes peeled as this is further developed. http://asteriskradio.net/wp/2009/04/29/digital-integration-to-pstn/

And here are some thoughts on using a SIP phone/client on an Iphone or Android phone to connect to D-Star.

Here is a bit more of John's thinking. A cut and paste from an inquiry to the rtpDir yahoo group:

Subject: Re: Question on Dstar-Asterisk Integration
Date: Thursday, July 23, 2009 3:56 PM



--- In rtpDir@yahoogroups.com, "Tom Power" wrote:

Question for the Group:

Does Scott, KI4LKF's Dstar to Asterisk integration allow the passing of the Dstar integrated callsign in the Dstar Stream to Inbound Caller ID on Asterisk/SIP?

Wondering the level of integration with Asterisk.

Thinking of doing some experimenting....
Was thinking on a PBX integration point. Basically two ID-1's with one of the ID-1's having an asterisk server on one end and using it as a Autopatch, announcement system, SMS Gateway etc.

Thanks,
Tom

As Scott said, that is not what his code does, but it is something several folks have a strong interest in seeing implemented.

Now that open source (Scott's and G4ULF) gateway implementations are coming about, the integration should be a lot more approachable.

Here is what I would like to see.

A driver on Asterisk that has the following functionality:

* It creates a channel to D-STAR where an extension or DID could be mapped to a D-STAR callsign. This channel would do a few things:

Route the stream through an AMBE device (such as the DV Dongle) and bi-directionally transcode between the source CODEC (GSM, G.711, etc.) and AMBE.

It would initiate a "ring" to the D-STAR network through a gateway, setting the UR field to the destination callsign and the MY field to a callsign assigned to the PBX (e.g. KX1XXX T - T for telephony interconnect). The "caller ID" would be placed in the Icom defined 20 character short message field, so that it would show up on the display of D-STAR radios on the radio side of things. It could also send an "audio" indicator of a ring in the stream.

When the radio receives the "ring", the radio user sends back a DTMF command such as "*" to answer, "#" to hangup, "1" send to voicemail, "2" send to my landline, etc.

If no command is received within a certain amount of time, the call is sent to Voicemail.

The conversation takes place (with predefined timout).

If there is also text from the same session (e.g. Jabber/SIP) it is put into the data stream on D-STAR, so it will be available on the data port on the radio. (Bi-Directional)

At the end of the conversation, the radio user sends a DTMF hangup command (e.g. "#") - since this is connectionless, if the "telephone" user hangs up, the DTMF is unnecessary.

Conversely the radio user, sets up a call by setting up his radio:

UR: KX1XXX T
RPT1: KX1XXX A (the repeater)
RPT2: KX1XXX G (the gateway -- I think this should be removed in the future, but its how it works now)
MY: K7VE

The radio user sends a DTMF sequence to start the patch, such as "*123", then dial the number/extension you want to call and proceed like a "regular" telephone call. Then hangup using a DTMF command.

BTW, all of this should work through the D-STAR network. So you could actually go to a remote "registered" Telephony Interconnect. E.g:

UR: KX1XXX T (Boston Interconnect)
MY: K7VE (I'm in Seattle)
RPT1: K7LWH C (2 meter Bellevue WA Repeater)
RPT2: K7LWH G (Bellevue WA Gateway)

Pretty cool?

Once this is all working it is simple to use the Asterisk PBX for voicemail, interactive voice response, etc.

I am gathering the components to build a "desktop repeater" for testing, at which point I hope to work on this.

-- John, K7VE

http://www.mail-archive.com/dstar_digital@yahoogroups.com/msg02975.html

{Edit 1/2011}
Karl, N2VQM posts some good thoughts on the whole matter:
http://groups.yahoo.com/group/gmsk_dv_node/message/6210

3.5 GHz HSMM

High Speed Multi Media (HSMM) is often referred to as being the Hinternet (Ham Internet), as it is primarily used under FCC Rules & Regulations Part 97. Under Part 97 commercial off-the-shelf equipment can be used at higher power and higher gain than the more common Part 15 802.11a/b/g operations.

The primary purpose for HSMM and Hinternet is to augment emergency communications via long range high speed wireless data networks that can handle voice, data and video communications. HSMM can also be used in the day-to-day aspects of Amateur Radio Communications.

---

One direction the High Speed Multi-Media Working group had was to develop in collaboration with TAPR, 3.3-3.5-GHz transverters suitable for use with 802.11 gear.

The thought is with the seemingly infinite amount of consumer wireless devices being deployed worldwide, the shared 2.4 GHz and 5.8 GHz noise floors are rising. The 3 GHz ham allocations are from 3.3 to 3.5 GHz yielding over 30 better suited non-overlapping full-width channels unshared with Part 15 unlicensed devices.

Ubiquiti Networks is a new company founded in 2005. Their "frequency freedom technology, seems to lead the way and promise integrated radio technology which uses an advanced RF integration and firmware design to provide a powerful platform capable of operation in any frequency imaginable. Basically Ubiquiti radios are Atheros chipsets with transverters onboard.

There are three different Ubiquiti XR3 frequency ranges that are version dependant (hardware limited ranges): XR3-2.8 (2.70-2.90 GHz), XR3-3.5 (3.40-3.70 GHz), and XR3-3.7.

The Ubiquiti XR3 XtremeRange3 is a mini-PCI Adapter 3.5GHz 400mW and lists for $240. The price is still considerably lower that an Icom ID-1 implementation and yields much higher throughput.

I few months back I blogged about their Nanostation. I have been finding the Atheros chipset ability to utilize 5 MHz channels very handy for side-stepping interference.

Well, they have out done themselves. At a starting MSRP of $49, NanoStation Loco provides a breakthrough in cost, reliability, & performance. It also is supported by a Linux SDK to encourage open source development.

NanoStation2/5 “LOCO” - This dual-polarity (auto-switching/diversity) 8db antenna has 100mw output and POE (18V). The 5ghz version comes with 13dbi integrated antenna. The NS2/NS5 “LOCO” does not have external antenna connector like the standard NS2/NS5. It's also a little less powerful, only 20 dBm (100 mW) instead of 26. (400 mW).. Keep in mind after market firmware hacks let you do nearly one watt with the normal NS2, so this is likely a low ended report of what is actually capable of.

If you need an external antenna, never fear http://ubnt.com/products/bullet.php

For the curious, here are some internal pictures of some Ubiquiti products

{Edit}
Check out Steve Ford's (WB8IYM) Eclectic Technology Column in QST June 2009
Titled "High Speed Multimedia at 3.5 GHz"

Over the air D-Star to Asterisk- not far off

Erik, OH2LAK shows in this PDF how to use Jakub Hruska's D-Star decoder program in conjunction with the DV Dongle to receive D-Star audio off a analog radio using it's 9600 baud discriminator port.

Jakub's program is windows based and doesn't appear to include his source code. My hope is he will work with Scott, KI4LKF who seems very talented at programming so there can be some code convergence to help make a more stream-line way to decode the AMBE audio and map it to an Asterisk platform.



Scott already proved the Asterisk guys wrong. They reasoned that after you decode D-Star audio into 16-bit, monophonic, 8 KHz, SLE data, it would be impossible to encode it into ADPCM or u-Law or GSM or just LINEAR because it would become un-readable to IRLP or Asterisk or Echolink users.

This is interoperability at it's finest. An example of amateur radio working towards convergence with the real world. Typically it seems were are continually trying to set ourselves apart.

What a great display of what amateurs can still do, working together.

{Update}
Jonathan, G4KLX has developed code and Linux tools to decode the D-Star data similar to Jakub's program.

Flashable firmware?

Have you ever wondered why more ham manufacturers don't make the firmware flashable like everything else is these days? That way when there is a bug, or a need for a feature they can fix it or add it without having to recall the radio. The ability to update the firmware so bugs that become apparent in use can be fixed.
The ham manufactures tend rush their products to the shelves to beat the completion to the punch. However many times firmware bugs are discovered on the release of radios.

Yeasu and Icom are a good example of this. For example; some of the early release popular FT-8800R mobile radio had an audio problem that cropped up after using it in crossband mode. The work around was to power down the radio after exiting the crossband function. Many people sent their radios back in to have that firmware bug fixed, as do many owners of many other radios.

Two of the new Kenwood's apparently can now be flash upgraded in the field. (Amazing... Finally a ham manufacturer did that!)
http://www.kenwood.com/i/products/info/amateur/software_download.html

Flashable firmware also opens the door to later feature enhancements. For example the FT-8800 also lacks a CW ID for crossband, and something like that could easily be worked into a user downloadable flashable update. Or the new D-Star compatible IC-2820 that has reported audio and callsign display firmware bugs.

So I don't know why any modern design wouldn't use flashable firmware. One would assume the issue is cost. It's a much less expensive to do upgrades when programming faults and misdesigns happen if you ask me.

DV Dongle

If you have been following my blog you probably say my piece on interoperability strides and my other piece on this second roll out of D-Star called NXDN.

This interoperability thing as you can imagine is pretty important. The key problem stems from a lack of standards but it really has to do more so with the fact that technology is developing so quickly that it's difficult to get everyone on the same page. Technology standards seem to be set by who can develop something first and obtain the largest market following. Just look back at VHS vs Beta, Blueray vs HD-DVD, etc.

As pointed out a common interconnection that both P25, and D-Star developers are choosing is the standardized Asterisk based SIP protocol using RTP audio streams.

A key component in all these digital voice systems is the vocoder. This is the device that converts your spoken voice to a synthesized or digitally compressed speech format.

The public safety APCO/ P25 format uses Improved Multi-Band Excitation (IMBE). This is proprietary vocoder developed by Digital Voice Systems, Inc. (DVSI). It is the predecessor of their Advanced Multi-Band Excitation (AMBE). It costs $150K to get the rights to play with that mode plus $5 a seat. There is no off the shelf IC to do it.

D-Star uses Advanced Multi-Band Excitation (AMBE) from DVSI. Same $150K if you want the software source but they do offer a single chip solution for $20 single quantity and are happy to sell to hams.

The DV dongle is an important development. It was started by Moe, AE4JY and Robin, AA4RC. It contains the ability to process AMBE full duplex. Presently software applications exist to use this to communicate from a computer to a D-Star gateway. Further development are expected so that it can be interfaced to a radio's packet radio port that has the necessary discriminator connections. This may be a huge milestone. The ability to retrofit an existing repeater could be possible with this. Not only that, but you may be able to retrofit it in such a way that it can be usable in analog and for D-Star. 

With the DV Dongle you will be able to use DPLUS* or the future OpenDSTAR gateway software to connect to the gateway computer behind the ID-RP2C (repeater controller). Then you will use the DV Dongle to extract the audio streams and can transcode them to standard G.711a/u, GSM, G.729, etc. and then use the Asterisk PBX power for telephone, voicemail, DID-Callsign-DID, repeater, etc. interconnection.

(* DPLUS is a gateway addon daemon that provides a number of functions see: http://opendstar.org/tools/readme.txt)

When you take a digital radio platform like D-Star, this is where integrating Asterisk could be very powerful. Since the call sign is part of every packet, this could be assigned to a direct inward dialing number (DID) or extension.

At the present time the dongle connects over the internet to an Icom gateway controller at a repeater site. So for now is a non-RF application.

What would be even more ideal since D-Star radios don't have an analog packet port is if the various D-Star radios had a digital interface port/jack to support just such a dongle / device to transcode to a SIP and codec standard. Unfortunately at this time there are no known interfaces to the Icom D-STAR radios that allow access to the on-air data stream.

I'd love it if I could buy a D-Star radio, that has an digital interface of sorts. Something along the lines of D-Star non-proprietary interface. Perhaps a mini-USB interface that perhaps transcodes to a more open standard codec like G.711 using SIP and RTP protocols (standardized protocols) so one can connect the radios together into wide area networks.

Then one would be able to have a D-Star radio in my shack also interconnected to various Asterisk powered applications in their house. Where if you weren't around to take a directed D-Star call, it could be configured as a DID to a system and use a ring group / follow me list to let the radio caller ring a home phone or leave a voice mail.

The open source project25 interface is a good idea. Unfortunately the problem they're facing is that most of the manufacturers don't bother following the ISSI spec, nor does the ISSI spec call out hardware interface details. So basically the "plugs" on the back of say, a Quantar... don't match the "plugs" on the back of a MASTR III.

http://en.wikipedia.org/wiki/P25_ISSI

The Project 25 Inter RF Subsystem Interface (P25 ISSI) is a non-proprietary interface that enables RF subsystems (RFSSs) built by different manufacturers to be connected together into wide area networks.

It would be great to see an a D-Star radio that supports something like this on the market possibly before the P25 interface idea ever makes it to the market.  

ARRL: It Seems to Us: Interoperability October 1, 2007 We need to encourage D-Star manufactures to come up with a similar style non-proprietary interface for D-Star.  

Atheros

Atheros is a manufacture of 802.11 chipsets that are used by over 30 different wireless device manufacturers, including Netgear, D-Link and Linksys.
 
Just recently a totally open driver for these devices that talks directly to the hardware layer came into existence. Prior there was a partially open one in which operation out of the ISM/UNII bands was one of the developed features.

The real question now that this dam has been completely burst is what else can be done? Some hams wonder if they can be coded to handle doppler shift so that they could be used in conjunction with future AMSAT projects.

More info:
http://www.qsl.net/kb9mwr/projects/wireless/modify.html

Digital Voice Interoperability strides

Asterisk provides an Interoberabity platform

What is Asterisk?
Asterisk is an Open Source PBX & Telephony Platform. It’s often labeled as the future of telephony. It has been around since about 1999 and the platform is open source - Linux operating system based. It can support a variety of signaling protocols, but by far SIP, the session intitation protocol, for VOIP and other text and multimedia sessions, has become a standard.

For those scratching their head a bit... PBX stands for private branch exchange. It is a machine that handles many businesses telephones calls for you. Its main functions are to transfer calls to different individual phones; play music when somebody is put on hold; to play automated voice responses when a call is received; to provide an options menu for the caller etc.

Asterisk allows one to build their own phone systems. It adds features, functionality and reduces deployment costs in ways which; at first are a little difficult to understand.

How does this relate to amateur radio?

Very simple, the future of two way radio is digital. As of writing, TV are required to be full digital and shut down their analog transmitters in Feb. 2009. The only spectrum broadcasters are required to vacate are channels 64 thru 69 that will become the new "700 MHZ band" that is being auctioned off by the FCC. The vacated areas of this spectrum will be utilized for: Public Wireless deployment (Cellular/PCS); A wide-band private data network that will be shared between public safety and paying customers; and new spectrum for public safety that will butt right up to the re-located NPSPAC National Public Safety Planning Advisory Committee band being moved to 806-809/851-853 by Sprint/Nextel.

Public safety also has guidelines to migrate to APCO-25 digital. The future of two way radio is digital, and we must also advance in this direction. The digital premise is that it generally allows more use in a more efficient/flexible use of band space.

Most present day government communication centers that use analog systems happen to have a VOIP based dispatch console. This analog to VOIP patching is something that we are presently also embracing in ham radio with IRLP, EchoLink, Yeasu WIRES II, and the like.

Your seeing the digital migration in the commercial world as I pointed out; And the only analog part left of traditional telephone is the “last mile” drop to your home. Time Warner and now AT&T are providing digital phone service to close that up too.

As of writing there aren't any 100% directed approaches to tie this to the hobby that I can point you to. There are a number of open ended ideas from a variety of different people. What I'm saying is there is no one entity steering the ship, so to speak. This ideas are still in development. Which makes it precisely the time to jump aboard and get our hands in it and see what we can do with it. So in light of that I suggest a google search for more info...
Digital Voice Interoperability Software Strides
Perhaps some of you remember the ARRL "It Seems to Us: Interoperability" statement from October last year regarding emerging digital voice.

Well the good news is here are some of the strides I've run across:

-OpenP25 Project http://openp25.org/index.php/category/project-status/

"We've determined that the open source Asterisk PBX appears to be a good framework on which to build a P25 ISSI (Inter RF Subsystem Interface) switch. Asterisk has a mature SIP stack and already has the ability to transparently pass RTP frames between SIP channels. The National Institute of Standards and Technology (NIST) has made an open source program for ISSI testing freely available to the P25 community. A full-featured open source P25 ISSI switch is clearly achievable."

The Project 25 Inter RF Subsystem Interface (P25 ISSI) is a non-proprietary interface that enables RF subsystems (RFSSs) built by different manufacturers to be connected together into wide area networks. Apparently consideration is being given to enhancing Asterisk app_rpt to support a such a low-level P25 radio interface.
The open source project25 interface is a good idea. Unfortunately the problem they're facing is that most of the manufacturers don't bother following the ISSI spec, nor does the ISSI spec call out hardware interface details. So basically the "plugs" on the back of say, a Quantar... don't match the "plugs" on the back of a Mastr III.

-Open D-Star Project http://opendstar.org/

The OpenDSTAR group has released several software tools which build on existing commercially available repeaters and Internet gateways to extend functionality.

And this interoperability work in progress attempt has been around longer than the P25 one. They too are working a SIP stack into their DPLUS gateway add-on daemon.
A project is lead by Scott, KI4LKF expand the Asterisk capabilities with his RtpDir bridge software (Real TimeProtocol Director) software package for VoIP/RF Gateways. http://tech.groups.yahoo.com/group/rtpDir/
It can bridges transmit and receive from/to Asterisk/app_rpt, IRLP, Echolink, Speak-Freely and he is working on D-Star. There is support for all link interfaces, sound mode or ASCII mode, VA3TO, WB2REM, ULI, Rigblasters, MFJ, SignalLink, etc.
-RadioGrid RG-4 Radio Gateway. http://www.radiogrid.com/
The guys from NHRC who make repeater controllers have come up with a commercially targeted (and priced) controller called the RadioGrid RG-4 Radio Gateway. It's built around Asterisk open source PBX technology. It's specifically for VOIP linking designed with interoperability applications in mind. It uses a 500 MHz Blackfin processor, 64 MB RAM, 4 MB Flash memory, 1 GB SD Card

A key component in all these digital voice systems is the vocoder. P25 uses the IMBE vocoder from Digital Voice System Inc. (DVSI). It costs $150K to get the rights to play with that mode plus $5 a seat. There is no off the shelf IC to do it. Fortunately D-Star uses AMBE from DVSI they do offer a single chip solution for $20 single qty and are happy to sell to hams.

- The DV Dongle http://dvdongle.com/
The DV dongle is an important development. It was started by Moe Wheatley, AE4JY and Robin Cutshaw, AA4RC. It contains the hardware ability to process AMBE full duplex. Presently software applications exist to use this to communicate from a computer to a D-Star gateway. Further development are in the works so that it can be interfaced to a radio's packet radio port that has the necessary discriminator connections. This may be a huge milestone. The ability to retrofit an existing repeater could be possible with this. Not only that, but you may be able to retrofit it in such a way that it can be usable in analog and for D-Star.

It would be great to see an a D-Star radio that supports something like this on the market possibly before the P25 interface idea ever makes it to the market. We should to encourage D-Star manufactures to come up with a similar style non-proprietary interface for D-Star. As unfortunately at this time there are no known interfaces to the Icom D-STAR radios that allow access to the on-air data stream.

It would be nice to see some agreement and standards in place amongst the various guys working on software solutions and the manufactures, to help make things more stream-lined. Either way people are working on interoperability solutions, toward convergence with open standard codecs like G.711 using real word protocols like SIP and RTP protocols so one can connect the radios together into wide area networks.

Then one would be able to have a D-Star radio in their shack also interconnected to various Asterisk powered applications in their house or abroad. Where if you weren't around to take a directed D-Star call, it could be configured as a DID to a system and use a ring group / follow me list to let the radio caller ring a home phone or leave a voice mail. Calls could be route to/through the Public switched telephone network and so on. A very powerful ability for EMCOMM and personal use.

How to install a PL-259 (UHF) Connector with common tools

We took some raw footage in an attempt to put together a video to be used in conjunction with the hamcram and to put on youtube. Till that's done being edited, this is some stills and notes.

There are a few decently edited video's on youtube on how to install the common PL-259 connector. What seems notably absent is the explanation of tools to get a good heat transfer and to get a good looking solder job on the braid holes.

The best documentation I've see is the article on eham, but he uses a non-common 80 watt Weller, but also note his modified tip! If your read the comments from other, some use the two iron method that I will attempt to further describe.

It is rare to find a soldered one done decently. I think most hams simply do not put the time or money in the biggest part of the performance equation, which is the feedline and antenna. This explains why most installs are not grounded, which does far more than provide lightening protection. The performance of an antenna system and it's ability to radiate an efficient signal is directly related to RF grounding. A shoddy soldered braid is mistake number one.

Note: If you cannot solder the connectors correctly, I do believe you are better off with a decent crimp connector, such as RF industries. Larger diameter cable, especially LMR-400 with the aluminum foil is increasingly more difficult to solder properly. Consider buying crimping tools if you do more than a few connectors a year, it will be well worth it.

Start off with two Radio Shack 40 watt irons (64-2071). The solder should he 60/40 rosin core, .062 diameter. You'll also need a pliers and course file.

For most people, soldering the center conductor is not an issue. The trick to obtain proper heat transfer so that the braid holes is to clip the point off the soldering iron using a pliers, and file it a bit so that the iron fits in the braid hole.

The reason for two 40 watt irons is because honestly 40 watts isn't enough. But it's pretty hard to do these with a gun. The iron will go cold when soldering the connector neck's braid holes. This is due to the heat sinking action of all the metal.

rtpdir bridge

The rtpdir bridge - to bridge EchoLink, IRLP, D-Star and Asterisk http://tech.groups.yahoo.com/group/rtpDir/ by Scott, KI4LKF

This group was set up to host the RtpDir bridge software(Real Time Protocol Director).

RtpDir is a VoIP software for Amateur(ham) operators. It can also be used on other bands, Government, commercial and private nets, or direct user to user without any radios connected.

If a band requires an FCC license, it is the responsibility of the end-user to obtain one. rtpDir runs on Linux or Windows platforms. NEW FEATURE: *Asterisk*/app_rpt PBX interface. There are 3 versions: Linux GUI, Windows GUI, Linux(text mode).

It can be used on the Amateur bands, Government, commercial and private nets,
or direct user to user without any radios connected.
If a band requires an FCC license, it is the responsibility of the end-user to obtain one.

3 versions: Linux GUI, Windows GUI, Linux (text mode).
To download, click on "Files".

Basic features:
================

Bridges and RX/TX from/to D-Star, Asterisk/app_rpt, IRLP, Echolink, Speak-Freely.
Create and operate your own private VoIP net.
Full-featured IRLP and Echolink node(link, repeater, ...).
Multiple Asterisk, Echolink nodes are accepted even when an IRLP node is connected.

Basic features:

* Runs as Echolink/Echolink conference, IRLP reflector/Echolink conference, Echolink+IRLP, private net.
* Accepts *Asterisk*/app_rpt connections
* Can transmit to *Asterisk*,IRLP,Echolink using computer mic or radio
* Graphical environment.
* DTMF control from Windows or Linux
* Control your Asterisk nodes directly using IRLP DTMFs.
* Control your IRLP node directly using Asterisk DTMFs
* Remote text command control using ssh/Linux or PuTTY/Windows.
* Can TX/RX IRLP messages without the IRLP board.
* Any station can connect to rtpDir bridge. It does not have to be IRLP or Echolink
* GSM, ADPCM, LINEAR codecs are supported.
* Protocol conversion between IRLP, Echolink and *Asterisk*/app_rpt
* ADPCM, u-Law, GSM, AMBE(with DVSI chip) codec transcoders included.
* Protocol conversion between D-Star, Asterisk/app_rpt, IRLP, Echolink, Speak-Freely.
* DTMF processing internal(built-in) or External(hardware).
* Morse code IDs or Voice.
* COS "sensing" or VOX or both.
* Support for all link interfaces(sound mode or ASCII mode, VA3TO, WB2REM, G3VFP, G4CDY,...Rigblasters, MFJ, SignalLink,...)
* No need to buy the Asterisk URI board or modify a USB sound fob.
* No need to buy the IRLP board.
* Mark a station as "Mute", "Deaf" or "Mute and Deaf".
* Timeouts for login, download, connection.
* Activity reporting.
* Audio recording and playback.
* RF station identification(audio, CW).
* Welcome message(audio, CW or text).
* Recording, playback and controlled announcements.
* Convert text to CW.
* Runs as server or client.
* Interfaces with external scripts.
* Runs with or without a soundcard.
* Audio signal strength indicator.

Two-Tone Pager Decoding Using Multimon

Here is a handy Linux based project that I recently worked on for a friend who happens to be a volunteer fire fighter.

A lot of rural volunteer fire departments still rely on the Motorola two-tone sequential paging system and analog Motorola Minitor pagers for dispatching their crews to a fire scene. The standard "Motorola Quick Call 2" paging protocol consists of playing two separate audio tones, the "A" and "B" tone. The "A" tone is played first for one second, then the "B" tone for three seconds. Both of these tones are transmitted on the fire dispatch frequency (VHF usually) which the pager is tuned to. Inside the older Minitor pagers, a mechanical reed is used to filter and decode each of the proper tones. While this may sound primitive, it is actually very reliable. A modern tweak to this type of paging system would be for the fire dispatch page to also be sent to your computer or cellular phone via text or email message. That is what this project will attempt to cover, with the pager tone decoding being done in software instead of having to tie up an additional pager.

For the tone decoding software, I used a slightly modified version of Thomas Sailer's multimon Linux radio transmission decoder.

{Update 2013}
Someone forked the original Multimon.  The original version was badly in need of updating for compatibility with modern Linux installs.  The fork is called multimonNG.


http://dekar.wc3edit.net/2012/05/24/multimonng/

In addition to showing how to modify the source code to match the tone sequences you want to monitor, there is a patch to enable a "quiet output" option to the DTMF decoding and also flushes stdout for better reliability when used in this application. A potential Perl script to trigger an external commands such as start recording or send a text message/email to ones phone is included.

You can read more about the specifics here.

High Speed Multi-Media using Ubiquiti

This comes from David Josephson, WA6NMF about the New Ubiquiti access point/bridge/CPE:

It can't get much cheaper than this. Ubiquiti has started shipping its "NanoStation" radios in 2.4 and 5 GHz. With the appropriate country code selected, the 5 GHz unit will cover the entire amateur allocation 5660-5925 MHz, not just the ISM/UNII frequencies. Even the 2 G.4 GHz version is capable of operations in the 2.3 GHz amateur portions of the band. 5, 10 and 20 MHz wide channels, Atheros chipset, 400 mW radio, 802.11a protocols, in a molded weatherproof case with 13 dBi antenna, dual polarization, plus external SMA antenna connector, entirely open source firmware available in an all-in-one SDK for free which you can alter and compile yourself. With power-over- ethernet injector and 12 volt wall wart, $79 for 2.4 GHz or $89 for 5 GHz.

With DD-WRT v24 rapidly nearing completion we are proud to present support for all Ubiquiti devices (LS2, LS5, NS2, NS5, PS2, PS5) for the latest release candidate RC7. The associated firmware versions are part of the line of DD-WRT firmwares for professional use. Ubiquiti offers affordable yet powerful devices based on Atheros wireless technology and allows high performance long range Wireless LAN connections, especially when driven by DD-WRT.

http://www.dd-wrt.com/dd-wrtv3/community/developmentnews/1-common/21-dd-wrt-for-ubiquiti-devices.html


http://www.ubnt.com/

What is Asterisk?

Asterisk is an Open Source PBX & Telephony Platform. It’s often labeled as the future of telephony.

PBX stands for private branch exchange. It is a machine that handles many businesses telephones calls for you. Its main functions are to transfer calls to different individual phones; play music when somebody is put on hold; to play automated voice responses when a call is received; to provide an options menu for the caller etc.

Asterisk allows one to build their own phone systems. It adds features, functionality and reduces deployment costs in ways which; at first are a little difficult to understand.

How does this relate to amateur radio?

Very simple, the future of two way radio is digital. As of writing, TV are required to be full digital and shut down their analog transmitters in Feb. 2009. The only spectrum broadcasters are required to vacate are channels 64 thru 69 that will become the new "700 MHZ band" that is being auctioned off by the FCC. The vacated areas of this spectrum will be utilized for: Public Wireless deployment (Cellular/PCS); A wide-band private data network that will be shared between public safety and paying customers; and new spectrum for public safety that will butt right up to the re-located NPSPAC National Public Safety Planning Advisory Committee band being moved to 806-809/851-853 by Sprint/NEXTEL.

Public safety also has guidelines to migrate to APCO-25 digital. The future of two way radio is digital, and we must also advance in this direction. The digital premise is that it generally allows more use in a more efficient/flexible use of band space.

Most present day government communication centers that use analog systems happen to have a VOIP based dispatch console. This analog to VOIP patching is something that we are presently also embracing in ham radio with IRLP, EchoLink, Yeasu WIRES II, and the like.

A different hardware board for each of these proprietary VOIP systems that you want to support is required. You also need a need a multi-port repeater controller, to support each hardware boards analog breakout. This seems redundant to me, and is something that slows the advancement. IRLP seems to be the system of choice because it runs on the Linux operating system. This is because Linux is much more stable that Windows, and is an open source development.

Your seeing the migration in the commercial world as I pointed out; hello digital TV. And the only analog part left of traditional telephone is the “last mile” drop to your home. Time Warner and now AT&T are providing digital phone service to close that up too.

I really feel there "Could be" something big with Asterisk Telephony and perhaps D-Star. The marriage seems natural. I even think it can be integrated with existing VOIP systems like D-Star and EchoLink.

I feel anything is only a "could" type of thing, only because of how the concepts are presented to the amateur audience. This hobby is supposed to be about advancing technology...

As of writing there aren't any directed approaches to tie this to the hobby that I can point you to. There are a number of open ended ideas from a variety of different people. What I'm saying is there is no one entity steering the ship, so to speak. This ideas are still in development. Which makes it precisely the time to jump aboard and get our hands in it and see what we can do with it. So in light of that I suggest a google search for more info... Once you get interested you're likely to bump into myself or other hams on various message boards. And you will likely also have run across a few ideas on how to integrate it to the hobby.

If your interested in giving Asterisk a test drive I found this video overview a good starting point for myself. AsteriskNOW, or PBX in A Flash are both good starting places. They are a Linux install with Asterisk and a Asterisk GUI rolled into a bootable ISO CD install.

Second roll out of D-Star

The second phase or revision of D-Star is out there. Both Icom and Kenwood are selling radios for it, it's general name is NXDN - FDMA.. It's know as Icom IDAS (Icom Digital Advanced System) and Kendwood calls it NEXEDGE.

NXDN Forum Announces its Formal Establishment

This is a brand-new digital format was co-designed by Kenwood & Icom that is geared towards the business sector. It is designed for those that want to meet the up-coming FCC mandate for 6.25 KHz channel spacing, but that can't (or don't) want to move to the APCO P25 Phase-II equipment that will soon come to market. The format is based on the AMBE+2 voice codec (similar to ICOM's D-STAR), but uses a 4-level FSK modulation (FDMA). The radios are capable of narrowband analog, along with 12.5 KHz & 6.25 KHz digital emissions. Kenwood is offering the system under the name NEXEDGE, and the radios are capable of both conventional & trunking operation. The attached sound file contains all of the formats the system is capable of producing, including the raw data streams of both digital formats.

D-Star, developed by ICOM, is the forerunner to the commercial counterpart of the technology we now know as IDAS (ICOM Digital Advanced System).

IDAS, also known as FDMA is the system generally best suited for commercial use since it meets all FCC technical standards through 2018 and is backwards compatible with 25 kHz, 12.5 kHz analog systems plus capable of operating in the digital mode on 25, 12.5, and 6.25 kHz channel spacing.

We have been to be Icom's lab rat for their rollout of commercial P-25 Phase-2 products. It's nice to know that the AMBE codec that was chosen for D-Star is slated to replace the IMBE codec in Phase 2 of APCO 25. For once it puts us as ham radio operators into state-of-the-art in communications for the first time in about 10 years. It's so nice to say that.

Audio sample

It uses AMBE+2 codec and 4FSK (4 level FSK) / FDMA (frequency-division multiple access scheme) digital modulation. AMBE+2 codec is compatible with IMBE used by P25 phase I.

NexEdge/IDAS was built off D-Star. Unlike D-Star, the NXDN repeaters can repeat analog or digital so you can have a smooth user migration.

It supports unit ID auto-roaming/registration much like how D-Star works.

Looks like the pricing to get going with NXDN will be about half the cost of D-STAR implementation. NXDN is like MOTOTRBO in that it can support mixed mode, but whats nice unlike MOTOTRBO & D-Star is more than one manufacture making radios & costs less on both accounts.

An ID-RP2C Repeater Controller for D-Star runs about $1500. You need to add an band specific RF voice module such as the ID-RP2000V for 2 meters which is another $1400

Where as the Icom IC-FR5000 Series VHF and UHF Repeaters run about $1500. This NXDN route also provides the analog/digital mixed mode backwards compatibility that D-Star doesn't.

The user end radios between D-Star and NXDN appear to be very similar in price.

The best overview I have found:
http://www.mygmrs.com/nxdn/index.php

I'd like to think that now since Kenwood is making AMBE Digital voice radios for their Nexedge, that one might see a Kenwood D-Star radio here in the US in the not to distant future.

If they do this, I hope they can improved upon the current Icom line.

Shell script examples

Here are a couple bash shell scripts that I've written for the Linux/Asterisk telephony platform. I'm sharing them as that's the free software spirit. I know they can serve as working examples for someone else who might have a similar project.

The first one determines the ice cream flavor of the day by reading a webpage, and converts text to speech, to be read over an Asterisk Telephone extension
or similar. http://pastebin.com/f3e743416

The second, determines the current weather conditions and short forecast by reading data from the weather service, and converts text to speech, to be read over an Asterisk Telephone extension or similar. http://pastebin.com/f33f75836 See also: http://www.qsl.net/kb9mwr/projects/wxalert/plan.html

The Linux operating system has all the tools to write your own programs and scripts. This is why I support it. Read up on Richard Stallman and Open Source Initiative.

http://en.wikipedia.org/wiki/Richard_Stallman

http://en.wikipedia.org/wiki/Open_source_movement

I'm not a total Winblows basher.... for the average person it has its place. But bigger business and people who need reliability ought to have their head checked if they are still banking on Microsoft.


In my case, I'm a hobbiest, and the Windows platform simply just doesn't do it for me. It's not flexible enough for me to be able to learn something.

Experimental 900 MHz Ham Radio Repeater

What I like about 900 MHz is that there are no off the self radios that you can buy. That may sound crazy.  But I wanted a project where I could get back to the basics of the hobby and learn a few things in the progress.

I created a 900 MHz overview on my the projects part of my webpage.  I hope this can prove to be a great overview of getting going on this band. I have received many compliments from others already.

Below is the start of documentation to a 900 MHz repeater that I have been working on.

It uses a 800 MHz Motorola Maxtrac as a receiver that has been converted to 900 MHz. See the Repeater Builders page on this: Converting an 800 MHz MaxTrac to a 902 MHz Repeater Receiver.  These are cheap and have great receive sensitivity. There are people on the AR902 list that sell them, with the conversion to conventional firmware already done. In some cases they have the filters pre changed or jumped too. These converted receivers can usually be found for about $60. On mine I replaced the filters with 915 MHz centered Murata filters rather than shorting as this provides further rejection from out of band pagers and what not.

A receive signal COR or CAS logic had to be exported so that you can interface the radio to a controller or have some signaling to be able to make the other radio go into transmit on reception of a signal. I like the Motorola M120, Maxtrac, GTX and GM300 line of radios as picking off a COR and exporting receive audio are all fairly simple and these mods can be work universally so you can mix and match these types of radios. You don't need the expanded 16 pin logic models. All the exports can be done using un-used microphone pins.

The transmitter is a 15 watt Maxtrac. These are good fairly rugged transmitters when compared to the other options such as the GTX.

I extended the MaxTrac 900 MHz VCO Frequency Range using a conductive ink pen. Obviously these radios were not intended to operate on the ham freq's. Even the radio's that are capable of this ham band that do not necessitate hardware mods, the programming software doesn't recognize amateur frequencies. At the very least you have to hex edit the software. Even after you trick it into letting you enter those frequencies, many of the radios' have VCO locking problems and won't transmit (or receive) in various sections of the ham band with out some of these hardware mods.

I also realized that I may later need a fairly dynamic control of the output power to meet various (low) drive requirements for an amplifier. The Radio Service Software allows for small power adjustments, but generally those software controls are considered unstable beyond a 3 dB adjustment.  So manual power control mods were necessary.

The duplexers are TX/RX. Contrary to what most assume, you can tune a duplexer with nothing more than a HT as signal source and watt meter. You don't really need a fancy service monitor. It's always desirable for greater accuracy, but not necessary.

There is some good info here: http://www.seits.org/duplexer/duplexer.htm

When I need very week signal to test a receiver or antenna a police scanner can do the trick. If you can find the IF (intermediate frequency) of the scanner, you can add that (10.85 MHz in my case) to the intended freq that you need a signal on. You should have a very week "birdie" where you need it.

I'm using a very simple repeater controller. It's the Ham Gadgets ID-O-Matic Kit. It's very small and only $20. I am also still experimenting on simplex with devising my own more multi functioned Linux based controller.

I also am using a Janel Model PF849D 900 MHz 10 dB 26 volt preamp that I picked up at Grayslake for $10.

This system is On the Air on 927.5125/902.5125 with a Digital PL of 223. It's presently into a crummy Maxrad MN9155 5 dB 900 antenna that I have at 45 feet on my tower feed with LMR-400. I have to say I am rather impressed. This is pretty cool considering the antenna gain probably makes up for the coax loss at best.

For anyone who might be from Wisconsin, I want to let you know that at the WAR meeting back at the end of April, the ARCC bandplan was adopted for 900 MHz use in Wisconsin. It's works much like the SERA bandplan, which is the well known one that accommodates both 12 MHz & 25 MHz repeater splits. The advantage of the ARCC plan is that it doesn't interfere with any existing areas for other modes like SSB/week signal, etc.

'ON THE AIR' 1937 - How Radio Works

A great explanation for a old film, and much of the information is still accurate. Perfect for use with entry level licence classes.

Surfin': Exploring 900 MHz

I just noticed I made Stan Horzepa, WA1LOU's column again:

http://www.arrl.org/news/features/2008/04/18/10054/?nc=1

The last time was 2002:
http://www.arrl.org/news/features/2002/10/26/1/

He writes a web column about stuff he runs into online. I kind of wish his column was part of the made the main stream publication. He writes about a lot of interesting stuff.

Transmitter Fingerprinting

It is true that transmitters can be fingerprinted for positive identification. Unidentified repeater kerchunks or even jamming are some times hard to figure out with common transmitter hunting techniques because its hard to tell if one short transmission is the same as the next, more so if they aren't stationary.

Transmitter fingerprinting is very easy to do if you have an fancy service monitor/ with digital storage spectrum scope.

Keep in mind the easiest way to stop a jammer is to ignore him. never mention or threaten a jammer on the air. He wants to hear how much you hate him. Keep your mouth shut and the problem will likely disappear.  

But if it doesn't, hunt stealth style. And if common fox hunting techniques aren't working out, and you don't have access to a spectrum analyzer here is some info on software approaches:

The concept of transmitter fingerprinting was invented and patented decades ago by Phil Farrell K7PF of Seattle. He licensed his patent/technique to The Boeing Company and to Motron Electronics, which sells equipment for it. The Motron implementation (called TxID) consists of a card that plugs into the expansion slot of a PC, plus software running under DOS. The asking price is higher than most individuals are willing to pay ($700), but it is affordable for repeater clubs. There was a test and review of the system in Homing In for November 1994. The review explains the principles of fingerprinting and shows good and bad points, including comparison of some same-model transmitters. Since then, Motron has added features such as receiver frequency control and readout for remote operation. TxID will control a tape recorder for evidentiary purposes.

The former Motron website explained how it worked:

The MoTron TxID Transmitter FingerPrinting hardware identifies individual transmitters using a patented technique based on the principle that carrier operated radio transmitters exhibit a unique frequency versus time start-up characteristic before stabilizing on the operating frequency. Carrier operated radio transmitters exhibit a unique frequency versus time start-up characteristic before stabilizing on the operating frequency - even radios of the same make and model. This 'FingerPrint' can be captured, stored and analyzed. The TxID Software, which can automatically match and compare up to 256 FingerPrints, and the TxID-1 IBM/Compatible circuit board will help us to identify the abusers on the repeater. An onboard fast squelch starts the FingerPrinting process. The voltage on the receiver's discriminator is sampled, digitized and stored. The leading edge of the carrier is then captured, stored and displayed. Other information about the signal is also captured, including DTMF, CTCSS and DCS signals with separate peak deviation readings, and displayed with the FingerPrint. The TxID System can optionally control a tape recorder, capturing all or part of the transmission on audio tape along with the digitally encoded FingerPrint data. Deviation measurements and Spectrum Occupancy features further enhance the system. The TxID System works with the Receiver, the TxID-1 can also capture the frequency of operation, as well as set the frequency.

For more info see: Testing Motron's Transmitter Fingerprinter by Joe Moell, K0OV - 73 Amateur Radio Today Nov 1994

A few hams have developed similar fingerprinting systems. The first was "XMIT_ID" by Richard Rager KB8RLN. It used PC software and an 8-bit Soundblaster card. Richard no longer has a web page about this software, but here is a mirror complete with the C source code in case some one would care to port this to a more modern operating system.

http://www.qsl.net/n9zia/xmit_id/index.html

I have played with Richard's DOS program and it does work. It has a small memory data base where you can tag and label the fingerprints for easier visual identification.

"Sherlock" by Malcolm Mallette WA9BVS also runs on a PC and uses its sound card with commercial oscilloscope software. 

From: Introducing "Sherlock" - A Hi-Tech Fox Hunting Tool by Malcom Mallette, WA9BVS - CQ-VHF Sept 1996

The Sherlock system is the modern equivalent of putting a scope across the discriminator. It consists of a simple AID converter, an audio amplifier, and software, and it captures the turn-on and turnoff so that the operator himself can draw his own conclusions. While not a clone of the commercial unit, or intended for commercial use, Sherlock also enables the operator to identify a transmission if he has previously captured, or later catches, the turn-on and turn-off of the same transmitter when the operator gives his callsign. This must be done manually. Sherlock's A/D converter is based on the Maxim MAX150 chip .

The newest version of Sherlock, which works with Windows XP and Vista, was detailed in a feature article by WA9BVS in the Winter 2006 issue of CQ VHF magazine.  It uses the the Virtins Sound Card Oscilloscope, instead of the original QuickBasic program.

XMIT_ID and Sherlock are intended for home experimentation only. Commercial production of any fingerprinting system based on the turn-on frequency changes of a transmitter may infringe on US patent 5,005,210.  

I thought this was neat: In the patent PDF there is assembly source code titled "S.R.G's New Repeater Controller 12/22/86 K7PF"

From http://www.qsl.net/srg/index.html

Seattle Repeater Group (SRG)'s highly computerized repeater is located "High atop Green Mountain" eight miles west of Bremerton, Washington on the Kitsap Penninsula. This repeater is owned by the Seattle Repeater Group and administered by Phil, K7PF. It is allocated the frequency pair 146.28/146.88.

The SRG repeater has several unique operating characteristics of which a user must be aware. A half second of audio silence is necessary to start the repeater. A weak signal may not start it, but can answer once the system is up. Any sub-audible tone will totally prevent startup. The repeater possesses a defense against Kerchunking.

The "courtesy" beep (at the end of each transmission") tells users that the repeater is available for use, and that all timers have been reset. It is actually not a tone but a direct FM data burst at 9600 bits per second which sounds like a tone, sometimes. If you have an IBM PC (or clone), with EGA or higher graphics, you, too, can read this data burst, identify users, and tell about the characteristics of each transmission. "

http://www.qsl.net/srg/operations.htm#KERCHUNK

"Kerchunking" (keying up and immediately releasing the microphone button) the repeater momentarily may result in a CW "?" or a "Please Identify" voice message. Nothing will have been repeated.

The repeater is immediately put into AUTOVOX mode and remains there until the next even minute (every two minutes.) Further Kerchunks have no effect.

One must exceed the 2 KHz LOW DEVIATION threshold to start the repeater while it is in AUTOVOX mode. Successful starting cancels the AUTOVOX (until the next Kerchunk, of course.)

http://www.qsl.net/srg/fingerprint.htm

Make your own vacuum tubes?

Fabrication d'une lampe triode
by F2FO

This French ham makes his own triodes. The link has a movie of him doing just that. And he does a noce job, even shows the final product working.

It's a long video at 17 minutes, but worth looking at. It was first blogged on the Make Magazine website. The first magazine devoted entirely to do-it-yourself technology projects. If you haven't heard of the magazine, check it out next time your at Barnes & Noble.


http://blog.makezine.com/archive/2008/01/make_your_own_vaccum_tube.html

And if your up to it:
http://www.sparkbangbuzz.com/crt/crt6.htm

Poorman's P25 / D-Star repeater using Maxtracs

This diagram on how to use two Motorola Maxtracs is from Tim Warth, AA2RS.

This is perfect if you don't have the 3 grand to put up a D-Star repeater or can't find a good deal on a Motorola Quantar for P25.

Remember this mod is transparent. ANYTHING it hears that breaks squelch, including intermod and spurious noises, will get repeated. Data is not regenerated.


As shown, the TX audio must be routed to the new point of entry, otherwise, it gets filtered and 4 level FSK won't pass. It's recommended to do the Maxtrac power mods and putting active cooling on the radios as these radios get hot.

In most cases a carrier system is less than desirable. Fortunately Rick Parrish, KD4VXY (the author of Unitrunker) has written a software based NAC decoder. Unfortunately at this time it it does not yet have support to provide a serial or parallel port logic output.

It's worth looking at the CML Microcircuits CMX7031, and CMX7041 datasheets. It's A C4FM baseband data processor chip.  After some microcontroller coding, this could work similar to how the D-Star node adapters work.  (Those typically use the CMX589AP4 chip)