I think it was about 15 years ago now that the ham radio license classes where consolidated down to three, from more than 5 different classes.
In that time I have been hoping someone would propose a new license class. I think there actually was a proposal that went no where to create a communicator license class. And about the same time the HSMM working group also proposed a licensing scheme.
More recently, while not a specific license class, Bruce Perens pushed for a major rules rewrite. His proposal had some good ideas to promote experimentation.
In order to keep ham radio relevant and interesting really relies on innovation from technically oriented hams. From there it usually progresses to small manufactures to adopt the ideas and put the stuff in the hands of many.
It wasn't that long ago that I myself was looking for a way to have a few of the outdated data rules relaxed so that I could experiment with 70 cm HSMM. And we are still in limbo on that many years later.
The quickest way to have rules relaxed so one can commence testing something new is to apply for Special Temporary Authorization (STA). A number of hams have gone this route over the years, and use that as a basis for a formal rule chance that benefits all hams.
The problem is that is a somewhat cumbersome bureaucratic process. The other problem is there are a lot of arm chair lawyers in the hobby. So if you don't go that route and decided to commence testing on your own, you risk really upsetting the community, even if whatever you are doing is only a little grey, and doesn't really impact others.
So I think we need an easier way to let the few folks that do the most good for the hobby (developers), get on with their ideas.
So I think introducing an experimenter license class is something to think about.
You ask, what would a new license class possibly offer anyone, as a general class license already lets you operate on all bands?
I am thinking those who took passed the experimenter license exam elements, are void of having to follow some of the rules.
Perhaps if they hold the experimenter license, their spread spectrum transmissions are not second class to all other modes, for example. Perhaps they are allowed to run wider data modes, etc.
I am sure its a contentious idea, but I do think, only a handful of folks would ever even pursue the license class, so it's impact would be minimal on normal operations. But I feel it would provide an avenue for more experimentation.
Wednesday, December 21, 2016
Tuesday, November 8, 2016
Digital voice stuff
It's been a while since I blogged on that area. There have been a number of proposed multi-protocol digital radios, and I guess I have been holding out for that.
And while KN4AQ's reddit post is a pretty good summary of the issues on why that is taking so long to come to be, it doesn't really touch upon the digital voice software experimentation and progress being worked up independently by hams.
Before I dive into that more, some commentary on Yaesu System Fusion. This was the later player to step to the plate in 2013. And while Yaesu has pretty much been my radio of choice over the years, I guess I had higher hopes figuring they learned a few things along the way, getting into it later.
Some things they did are done right in my opinion. At least their repeaters are backwards compatible with analog. It's a good marketing strategy for them. But mostly one doesn't have to launch another repeater specific to one mode. So it's a prudent move in terms of spectral efficiency. I mean don't we have enough idle repeaters already?
The whole external Wires X, controller and computer to provide external internet connectivity is horrid to me. I guess I was hoping for a repeater with a network jack, like DMR. I'd take that over all the touch screen sillyness.
On the user end of Yaesu System Fusion radios I am glad they are firmware updatable? (I know the repeater is for sure). It's really quite sad and dumb that the firmware is a closed deal, not open to 3rd party development. And the whole camera thing is really dumb in my opinion.
What I have decided to monkey with is MMDVM, which is a open-source Multi-Mode Digital Voice Modem project by G4KLX. It allows one to retro fit an existing analog repeater into one that supports, D-Star, Yaesu System Fusion, DMR and P25. I have my name down for the interface board and expect to be playing with this project soon.
I was thinking about the DV4mini and some of the other stuff like the DVmega, but I am turned off by the low power/ single user limitations. I have always been a fan of building/buying things a number of folks can use... the community approach.
Prior to DMR becoming popular in ham radio, and Yaesu introducing their Fusion stuff, Codec 2 made some sense. At that point it was pretty much just D-Star, and everyone was in a tizzy about it using a propriety codec/vocoder. Now there are so many different VHF/UHF digital radios out there using the patented technology, and there still isn't a drop in "open" replacement for VHF/UHF. Since all the major amateur radio players have their own digital radios, even if an open codec were available tomorrow, it would take a start-up company to adopt it and and a miracle to come up with a priced right radio that would potentially displace the existing digital market in the foreseeable future because as as noted there been a number of setbacks in developing multi-protocol user radios. And in one year the open source AMBE code for D-Star should be legal.
So that is where we sit for now, and probably quite a while. Sad, but true.
A couple years ago Bruce Perens gave a pretty good history/background speech titled "AMBE Exposed" What we need now are some specifics (a follow up talk). He talked about trying to invalidate the patent based on David Rowe's work and that DVSI made use of AMBE in commerce before their own patent applications.
Presently Jonathan's MMDVM (mutli-mode digital voice modem) repeater project has the capability to tie things together using multi-mode conference bridges. We have heard a little bit about a the CCS7 reflector system that is popular in Europe, that does just that to some extent too.
DMR, System Fusion DN, and NXDN all use exactly the same bit rate and FEC. "It's simply a matter of unwrapping the AMBE stream from whichever container format is used and wrapping it in the target format." Anything else may require hardware or a much better understanding of the patents.
Presently all the hardware dongles to deal with AMBE can only process a single stream at a time. This is less than ideal for anyone interesting is hosting a multimode conference reflector system.
The patent for IMBE for P25 may have expired. That is one thing that would be nice to get specifics on, as none of the hardware dongles really support that mode.
If someone were to start unwrapping the older AMBE that D-Star uses to create a software bridge to the newer AMBE+2 used in DMR, would that perhaps be permitted?
What algorithm is exactly protected by the patent? Obviously taking it all the way back to analog is a patented thing.
Which patents apply to IMBE, which to AMBE+, and which to AMBE+2?
When they expire how will be know for sure? If a commercial vendor were to seek the licensed code, is the patent holder under any obligation to inform the vendor its out of patent, and they may freely implement their own?
An example case of some other formerly patented technology, like Motorola's Private Line, or the like, and how generics came about might be a good explanation to many.
Note: For most U.N. member states; non-commercial/research usage of patented technology is covered by exceptions on the definition of "patent infringement." Actual practice may differ. Ref
And while KN4AQ's reddit post is a pretty good summary of the issues on why that is taking so long to come to be, it doesn't really touch upon the digital voice software experimentation and progress being worked up independently by hams.
Before I dive into that more, some commentary on Yaesu System Fusion. This was the later player to step to the plate in 2013. And while Yaesu has pretty much been my radio of choice over the years, I guess I had higher hopes figuring they learned a few things along the way, getting into it later.
Some things they did are done right in my opinion. At least their repeaters are backwards compatible with analog. It's a good marketing strategy for them. But mostly one doesn't have to launch another repeater specific to one mode. So it's a prudent move in terms of spectral efficiency. I mean don't we have enough idle repeaters already?
The whole external Wires X, controller and computer to provide external internet connectivity is horrid to me. I guess I was hoping for a repeater with a network jack, like DMR. I'd take that over all the touch screen sillyness.
On the user end of Yaesu System Fusion radios I am glad they are firmware updatable? (I know the repeater is for sure). It's really quite sad and dumb that the firmware is a closed deal, not open to 3rd party development. And the whole camera thing is really dumb in my opinion.
What I have decided to monkey with is MMDVM, which is a open-source Multi-Mode Digital Voice Modem project by G4KLX. It allows one to retro fit an existing analog repeater into one that supports, D-Star, Yaesu System Fusion, DMR and P25. I have my name down for the interface board and expect to be playing with this project soon.
I was thinking about the DV4mini and some of the other stuff like the DVmega, but I am turned off by the low power/ single user limitations. I have always been a fan of building/buying things a number of folks can use... the community approach.
Prior to DMR becoming popular in ham radio, and Yaesu introducing their Fusion stuff, Codec 2 made some sense. At that point it was pretty much just D-Star, and everyone was in a tizzy about it using a propriety codec/vocoder. Now there are so many different VHF/UHF digital radios out there using the patented technology, and there still isn't a drop in "open" replacement for VHF/UHF. Since all the major amateur radio players have their own digital radios, even if an open codec were available tomorrow, it would take a start-up company to adopt it and and a miracle to come up with a priced right radio that would potentially displace the existing digital market in the foreseeable future because as as noted there been a number of setbacks in developing multi-protocol user radios. And in one year the open source AMBE code for D-Star should be legal.
So that is where we sit for now, and probably quite a while. Sad, but true.
A couple years ago Bruce Perens gave a pretty good history/background speech titled "AMBE Exposed" What we need now are some specifics (a follow up talk). He talked about trying to invalidate the patent based on David Rowe's work and that DVSI made use of AMBE in commerce before their own patent applications.
Presently Jonathan's MMDVM (mutli-mode digital voice modem) repeater project has the capability to tie things together using multi-mode conference bridges. We have heard a little bit about a the CCS7 reflector system that is popular in Europe, that does just that to some extent too.
DMR, System Fusion DN, and NXDN all use exactly the same bit rate and FEC. "It's simply a matter of unwrapping the AMBE stream from whichever container format is used and wrapping it in the target format." Anything else may require hardware or a much better understanding of the patents.
Presently all the hardware dongles to deal with AMBE can only process a single stream at a time. This is less than ideal for anyone interesting is hosting a multimode conference reflector system.
The patent for IMBE for P25 may have expired. That is one thing that would be nice to get specifics on, as none of the hardware dongles really support that mode.
If someone were to start unwrapping the older AMBE that D-Star uses to create a software bridge to the newer AMBE+2 used in DMR, would that perhaps be permitted?
What algorithm is exactly protected by the patent? Obviously taking it all the way back to analog is a patented thing.
Which patents apply to IMBE, which to AMBE+, and which to AMBE+2?
When they expire how will be know for sure? If a commercial vendor were to seek the licensed code, is the patent holder under any obligation to inform the vendor its out of patent, and they may freely implement their own?
An example case of some other formerly patented technology, like Motorola's Private Line, or the like, and how generics came about might be a good explanation to many.
Note: For most U.N. member states; non-commercial/research usage of patented technology is covered by exceptions on the definition of "patent infringement." Actual practice may differ. Ref
Saturday, August 27, 2016
Wonder Woman on a radio
By now many have seen my old Ham Radio in popular culture project where I noted and made screens of various episodes of Family Guy, the Simpsons and the like that reference ham radio and two way radio use.
And even a few times I have made posts here on my blog pointing out the episodes.
This evening I was watching Wonder Woman on ME TV and "The Man Who Wouldn't Tell" episode (Season 2, Episode 20) depicts Diana Prince talking to Major Steve Trevor on a two way radio phone patch back to his office.
And even a few times I have made posts here on my blog pointing out the episodes.
This evening I was watching Wonder Woman on ME TV and "The Man Who Wouldn't Tell" episode (Season 2, Episode 20) depicts Diana Prince talking to Major Steve Trevor on a two way radio phone patch back to his office.
Saturday, August 13, 2016
Bridging digital modes
In Ham Radio Now, episode 263, Gary interviews Uli, AG0X about the DV4mobile.
Uli talks about the CCS7 reflector system that is more popular in Europe that allows interconnection of DMR, C4FM (Yaesu), D-Star with these reflectors.
This is a interconnection concept that has interested me since the days of Scott, KI4LKF who was probably one of the first to try and develop bridging solutions.
Granted when Scott was developing, DMR and Yaesu hadn't really existed or taken of yet. So his emphasis at the time was to bridge to existing VOIP networks like IRLP, Echolink, Allstar to D-Star.
It's clear to me that there won't be a digital standard in my life time. So Uli, and the others who are working on an end user digital radio that can support more than one digital mode are of interest to me. I gave D-Star a try early on, but am totally put off by all the walled gardens and digital fragmentation, that are all so prevalent now with all the different digital modes.
Uli talks about his DV4home unit that is capable of transcoding and mixing modes as it has 2 AMBE chips. It can receive traffic from one reflector and bring it back to “digital analog” (like and AVI file, its PCM.. 64 kilobit digital) and then re-encode it in another mode.
I had a DV dongle (the old blue one) for a while, but sold it after DMR came into play and I realized it's limitations. Now there are a number of different dongles to deal with the codec's. But what is not clear to me is if any of them are (or the software for them) able to process multiple streams simultaneously (multiplexing).
A reflector in the "cloud" can be equipped with the AMBE hardware if needed to process multiple streams and transcode between them to provide an interoperability bridge when folks need it to talk cross modes; makes total sense to me.
(I have read some references to DMR to YSF Reflector bridges that bridge the audio in software. "DMR, System Fusion DN, and NXDN all use exactly the same bit rate and FEC, so it's simply a matter of unwrapping the AMBE stream from whichever container format is used and wrapping it in the target format")
(I have read some references to DMR to YSF Reflector bridges that bridge the audio in software. "DMR, System Fusion DN, and NXDN all use exactly the same bit rate and FEC, so it's simply a matter of unwrapping the AMBE stream from whichever container format is used and wrapping it in the target format")
It's not clear to me if this exists entirely yet, but I know there are some hams in Florida (ironically) working on that with Asterisk as a core of it.
Sunday, June 26, 2016
Noise Study
So perhaps you read FCC Technological Advisory Council is initiating a noise floor inquiry That is something probably long overdue in my opinion.
I have often wanted to map the bad areas around town. Seems a Raspberry Pi computer with a RTL-SDR stick and a USB GPS could the basis of sampling the noise floor on various bands and logging that and the location.
And then a way to download this and overlay it on a map when you get home.
Seems like a good SDR project for someone. I kind of wish I knew how to do it myself.
I have often wanted to map the bad areas around town. Seems a Raspberry Pi computer with a RTL-SDR stick and a USB GPS could the basis of sampling the noise floor on various bands and logging that and the location.
And then a way to download this and overlay it on a map when you get home.
Seems like a good SDR project for someone. I kind of wish I knew how to do it myself.
Wednesday, June 22, 2016
Maxtrac's and such.
Maxtrac programming software for Linux/ Linux software for programming Motorola Maxtrac radios through a serial port:
http://batboard.batlabs.com/viewtopic.php?f=15&t=112424
https://github.com/iotatron/linrss
I love this, as the Maxtrac/Radius line is my favorite radio. No longer need DosBox.
Speaking of that line of radios. Here is well documented, channel (40 channels) steering a GM300 for a remote base: https://www.youtube.com/watch?v=ZY9pfy5F4hw
I have to say Skyler, KD0WHB is an amazing young kid with a lot of enthusiasm in the right areas.
On that DIY topic, I recently watched DX Engineering video where they interview the new ARRL CEO, Tom, NY2RF. Tom says If you want to forecast the future, you have to invent the future..." agreed!
http://batboard.batlabs.com/viewtopic.php?f=15&t=112424
https://github.com/iotatron/linrss
I love this, as the Maxtrac/Radius line is my favorite radio. No longer need DosBox.
Speaking of that line of radios. Here is well documented, channel (40 channels) steering a GM300 for a remote base: https://www.youtube.com/watch?v=ZY9pfy5F4hw
I have to say Skyler, KD0WHB is an amazing young kid with a lot of enthusiasm in the right areas.
On that DIY topic, I recently watched DX Engineering video where they interview the new ARRL CEO, Tom, NY2RF. Tom says If you want to forecast the future, you have to invent the future..." agreed!
Friday, May 20, 2016
Goodbye IRLP hello Allstar
Our former high school ham radio club has been running an EchoIRLP node since like forever.
With the advent of the Raspberry Pi I have been meaning to retire the old power hungry PC and go to a smaller form factor.
It took a while for a working Allstar image, but I am glad I waited and went that route.
The idea was to let some of our former members who were in college check in over Echolink. And we didn't like the idea of a Windows PC at the repeater site. Since then, members have permanently set foot outside of Green Bay where the repeater is. And a group of them in Milwaukee set up a repeater and were connecting the thing over Echolink on a somewhat permanent basis back to the Green Bay repeater.
Due to the silly design of IRLP, you can only make one connection at a time. This is majorly annoying in our situation. As it shuts everyone else out while you have that connection up.
We also have another subgroup who are experimenting with digital stuff, DMR and the like.
Connecting that back over IRLP is taboo. And well the whole IRLP thing is basically stupid at this point.
What I have deemed is IRLP made sense in the 1990's. Today it does not. It was the best at the time, but is no longer. It is not open source, which is something more and more over time I have felt strongly about in this hobby. I kind of had an awakening to all this with D-Star and the AMBE dilemma.
IRLP is based on the parallel port, which is getting harder to find in a PC. It has a single source hardware interface board, which again I have issues with. There is a big long list of no-no's in terms of use. Basically it's a dictatorship.
In short we all grew up, as we are no longer in high school or college anymore. It was time to move to a more grown up VOIP system, which was long over due.
With the advent of the Raspberry Pi I have been meaning to retire the old power hungry PC and go to a smaller form factor.
It took a while for a working Allstar image, but I am glad I waited and went that route.
The idea was to let some of our former members who were in college check in over Echolink. And we didn't like the idea of a Windows PC at the repeater site. Since then, members have permanently set foot outside of Green Bay where the repeater is. And a group of them in Milwaukee set up a repeater and were connecting the thing over Echolink on a somewhat permanent basis back to the Green Bay repeater.
Due to the silly design of IRLP, you can only make one connection at a time. This is majorly annoying in our situation. As it shuts everyone else out while you have that connection up.
We also have another subgroup who are experimenting with digital stuff, DMR and the like.
Connecting that back over IRLP is taboo. And well the whole IRLP thing is basically stupid at this point.
What I have deemed is IRLP made sense in the 1990's. Today it does not. It was the best at the time, but is no longer. It is not open source, which is something more and more over time I have felt strongly about in this hobby. I kind of had an awakening to all this with D-Star and the AMBE dilemma.
IRLP is based on the parallel port, which is getting harder to find in a PC. It has a single source hardware interface board, which again I have issues with. There is a big long list of no-no's in terms of use. Basically it's a dictatorship.
In short we all grew up, as we are no longer in high school or college anymore. It was time to move to a more grown up VOIP system, which was long over due.
Sunday, April 24, 2016
Converter box recorder
Many moons ago I dabbled with MythTV to record over the air TV. It's an open source home entertainment application. Then DTV came along and the tuner card hardware I had was going to need replacement.
Since then I have played with Kodi/XBMC, and OpenELEC on the Raspberry Pi. But I am using this much like a Roku box, just to compliment my TV watching. I often wish there was a modern DVR for over the air TV.
Recently when I was shopping the RCA DTA880 caught my eye. A digital converter box with recording. There is also the Ematic AT103B. Both can record over the air TV to a USB stick. This is awesome. Neither however have a network jack, as it would be nice to be able to play back/record to a network share. Another thing I wish it had was line input jacks, so you can record from an external source like a satellite.
Basically someone needs to combine these converter boxes with a Roku boxes for folks who are looking for options when considering dropping cable etc.
The Simple.TV boxes seem closer to what I am seeking as they are able to connect to the network. However they have a portal manged setup, and reportedly a Roku box can can act as a client to connect to the Simple.TV backend to stream live and recorded TV. I haven't found a simple way to use a Raspberry Pi running OpenELEC or what have you to function as a client in a similar way.
The Magnavox HD DVR/HDD 1TB ATSC Tuner has RCA inputs as well as coaxial for over the air ATSC. But I don't really care so much for the price. I'd rather add my own USB drive, so if it didn't have an internal drive, that would help the price a little.
Since then I have played with Kodi/XBMC, and OpenELEC on the Raspberry Pi. But I am using this much like a Roku box, just to compliment my TV watching. I often wish there was a modern DVR for over the air TV.
Recently when I was shopping the RCA DTA880 caught my eye. A digital converter box with recording. There is also the Ematic AT103B. Both can record over the air TV to a USB stick. This is awesome. Neither however have a network jack, as it would be nice to be able to play back/record to a network share. Another thing I wish it had was line input jacks, so you can record from an external source like a satellite.
Basically someone needs to combine these converter boxes with a Roku boxes for folks who are looking for options when considering dropping cable etc.
The Simple.TV boxes seem closer to what I am seeking as they are able to connect to the network. However they have a portal manged setup, and reportedly a Roku box can can act as a client to connect to the Simple.TV backend to stream live and recorded TV. I haven't found a simple way to use a Raspberry Pi running OpenELEC or what have you to function as a client in a similar way.
The Magnavox HD DVR/HDD 1TB ATSC Tuner has RCA inputs as well as coaxial for over the air ATSC. But I don't really care so much for the price. I'd rather add my own USB drive, so if it didn't have an internal drive, that would help the price a little.
Thursday, April 14, 2016
High Speed Multimedia for Amateur Radio Book - Review
I just received a copy of this new book by Glen, KW5GP. It worked out well as it was my birthday a week ago and I had that ARRL coupon to burn.
In the introductory first chapter it discusses Part 15 verses Part 97 operation. It goes on to talk about peer-to-peer mesh networks (AREDN and BBHN), verses the traditional spoke and hub network, star topology (HamWAN). Then it covers frequencies showing allocations on 2.4 GHz and 5.7 GHz, which channels overlap Part 15, and which are Part 97 exclusive. Then a bit about TCP/IP in general an a quick history of the AMPRnet.
Chapter 2 is about technologies. 802.11b/802.11g/802.11n and its ham use regarding some regulatory information on DSSS and OFDM. It then goes on to explain 802.11a/802.11ac. From there it briefly talks about the two main ham firmware projects; AREDN and BBHN. It later goes more in depth with the history of both and also explains HamWAN.
Chapter 3 talks about equipment. It starts off with the WRT54G, goes on the Ubiquiti, and Mikrotik. It covers connectors, feedline, antennas and brief mention of amplifiers.
TCP/IP for HSMM is the title of the next chapter. It talks about it's history and again a brief mention of ampr.org. Public IP space verse private, and goes on to break down the datagram explaining how it works before going on to explanation of the OSI model. It covers network classes, subnetting, MAC addresses and switching. Then it goes on to talk about IP routing and IP routing protocols, including static and dynamic routes, routing protocols like link-state routing protocols (OSPF), NAT and its downside, DHCP, DNS, and VLANs. It also talks about the troubleshooting tools, like wireshark, traceroute, ping, etc. A very thorough review on TCP/IP.
Chapter 5 is about Applications. VOIP/Asterisk/FreePBX, IRC/HamChat/OpenFire/ClearOS. It also covers Webservers, SMTP E-Mail servers, FTP servers, and network servers like NTP and DNS. Later in the chapter it mentions and shows a webcam and the Raspberry Pi as a platform for such previously mentioned servers.
Security and Filtering is the next chapter. It starts with physical, goes on to firewalls and filtering showing how with ClearOS again.
Chapter 7 is titled "Backup and Redundancy." It starts with power, recommending a UPS. Talks about ESXi for virtualization, network monitoring; SNMP and PRTG. It also talks about redundant links and atmospheric conditions.
Deploying is the next chapter. It tells you 2.4 GHz and re-purposed WRT54g's are likely the quickest and cheapest to deploy but warns you about congestion and network performance. It talks about wireless path planning with SPLAT and Radio Mobile. And explains the importance of Fresnel zones. From there it goes on to explain how to install the firmware be that BBHN or AREDN. And how to use and configure the firmware. It also dives int deploying HamWAN and MiktoTik setup.
Chapter 9 talks about The Future of HSMM and how its in a constant state of change. "All of the HSMM development groups are not content to sit idle with what they have done, but instead continue to push forward and improve upon what they have already accomplished." The author notes Ubiquiti gear offers the greatest flexibility for the future. He notes AREDN firmware allows the use of 900 MHz, 2.4 GHz, 3.4 GHz and 5.8 GHz and expects that we will see all of the HSMM technologies moving to the Part 97 only portions of the band to reduce noise floors which is already a capability of the AREDN firmware.
I have to say I am impressed by the book. And I have been playing with this stuff before 802.11b was ratified, as I started with FHSS gear, so for the book to impress me should really say something.
Its the ham radio oriented complimentary book to Wireless Networking in the Developing World.
In the introductory first chapter it discusses Part 15 verses Part 97 operation. It goes on to talk about peer-to-peer mesh networks (AREDN and BBHN), verses the traditional spoke and hub network, star topology (HamWAN). Then it covers frequencies showing allocations on 2.4 GHz and 5.7 GHz, which channels overlap Part 15, and which are Part 97 exclusive. Then a bit about TCP/IP in general an a quick history of the AMPRnet.
Chapter 2 is about technologies. 802.11b/802.11g/802.11n and its ham use regarding some regulatory information on DSSS and OFDM. It then goes on to explain 802.11a/802.11ac. From there it briefly talks about the two main ham firmware projects; AREDN and BBHN. It later goes more in depth with the history of both and also explains HamWAN.
Chapter 3 talks about equipment. It starts off with the WRT54G, goes on the Ubiquiti, and Mikrotik. It covers connectors, feedline, antennas and brief mention of amplifiers.
TCP/IP for HSMM is the title of the next chapter. It talks about it's history and again a brief mention of ampr.org. Public IP space verse private, and goes on to break down the datagram explaining how it works before going on to explanation of the OSI model. It covers network classes, subnetting, MAC addresses and switching. Then it goes on to talk about IP routing and IP routing protocols, including static and dynamic routes, routing protocols like link-state routing protocols (OSPF), NAT and its downside, DHCP, DNS, and VLANs. It also talks about the troubleshooting tools, like wireshark, traceroute, ping, etc. A very thorough review on TCP/IP.
Chapter 5 is about Applications. VOIP/Asterisk/FreePBX, IRC/HamChat/OpenFire/ClearOS. It also covers Webservers, SMTP E-Mail servers, FTP servers, and network servers like NTP and DNS. Later in the chapter it mentions and shows a webcam and the Raspberry Pi as a platform for such previously mentioned servers.
Security and Filtering is the next chapter. It starts with physical, goes on to firewalls and filtering showing how with ClearOS again.
Chapter 7 is titled "Backup and Redundancy." It starts with power, recommending a UPS. Talks about ESXi for virtualization, network monitoring; SNMP and PRTG. It also talks about redundant links and atmospheric conditions.
Deploying is the next chapter. It tells you 2.4 GHz and re-purposed WRT54g's are likely the quickest and cheapest to deploy but warns you about congestion and network performance. It talks about wireless path planning with SPLAT and Radio Mobile. And explains the importance of Fresnel zones. From there it goes on to explain how to install the firmware be that BBHN or AREDN. And how to use and configure the firmware. It also dives int deploying HamWAN and MiktoTik setup.
Chapter 9 talks about The Future of HSMM and how its in a constant state of change. "All of the HSMM development groups are not content to sit idle with what they have done, but instead continue to push forward and improve upon what they have already accomplished." The author notes Ubiquiti gear offers the greatest flexibility for the future. He notes AREDN firmware allows the use of 900 MHz, 2.4 GHz, 3.4 GHz and 5.8 GHz and expects that we will see all of the HSMM technologies moving to the Part 97 only portions of the band to reduce noise floors which is already a capability of the AREDN firmware.
I have to say I am impressed by the book. And I have been playing with this stuff before 802.11b was ratified, as I started with FHSS gear, so for the book to impress me should really say something.
Its the ham radio oriented complimentary book to Wireless Networking in the Developing World.
Saturday, March 26, 2016
Listening to local 700 MHz Simulcast public safety
This
post is somewhat geographically specific. For those seeking information on a police scanner for Green Bay/ Brown County. But I figured it was time to
share as folks in other areas are still having issues monitoring simulcast systems.
Shortly
after the new Brown County Radio System was put in place in 2013, I
discovered all the scanners on the market at the time could not deal
with simulcast as the county transmits from 8 towers at the same time.
Since
that time scanners with APCO 25 Phase 2 support have started to appear.
One would suspect a totally different receiver design for TDMA/Phase
2. I have heard reports that the Uniden BCD436 does handle simulcast pretty
well. (Yet the BCD996P2 does not)
Linear
Simulcast Modulation (LSM) is a trademarked term for a form of CQPSK
that provides a way for receivers to properly handle multiple identical
transmissions. It's just different enough that the regular C4FM
processing doesn't work correctly.
A
friend of mine has been able to successful listen using a Pro-106 using
an attenuator/ yagi combo. He lives in close proximity to one of the
towers with a line of site view. He effectively can listen to just one
tower with this approach. I was not successful with this method as I am
more centrally located and probably more importantly is that I do not
have a line-of-site path to any one site. So I have multipath
compounding the simulcast problem which is all too much for a C4FM
receiver design to handle.
Another possibility that I only briefly explored in early 2015 was trying to listen using a RTL SDR:
I ran into many headaches and never got it working correctly so I gave up. But I encourage others to give it a try. As time goes on, I am sure the software will be more refined and easier to get going. It would sure be the cheapest way to listen; a RTL dongle coupled with a Raspberry Pi micro computer would be ideal.
In
late 2015 I learned that local two-way dealer is selling XTS5000 radios
programmed as scanner for $900. He also can sell transmitting radios
to authorized users. Out of my price range but at least it's an option.
--
So
at the time (2013) the answer seemed to be to look into using a
commercial radio as a scanner. I choose the XTS-2500 as my radio based
on price and availability. Other capable radios include the XTS1500 and
XTS5000. From what I have seen the XTS1500 is usually comparable in
price to the XTS2500. However the chances of finding a used XTS1500
with the desired/required feature set is less common. Whereas the
XTS5000 is more common than both, but is typically more expensive.
I
totally lucked out and bought a refurbed demo radio from a Hong Kong
ebay seller that had little feedback for $250. Others have picked up
XTS2500’s for around $300.
There are a few different hardware models of the XTS2500.
Model 1: Basic, with no display
Model 15: Large bitmap display (a display is needed if you want to see what talk group it has stopped on)
Model
2: Large bitmap display and navigation buttons (the navigation buttons
are nice if you want to manipulate the scan list on the fly)
Model 3: Large bitmap display and full keypad (the full keypad has no advantage as a scanner)
There are two main features required for the XTS2500 to work on the Brown County System.
1.) First is has to be 700 MHz capable.
Rebanding support in the Astro25 platform was introduced in Host R07. - 1/3/06
The
model number theoretically dictates if the radio is rebanded of not. If
the model number ends in a "2BN" in the codeplug the radio will not do
700 nor will it be able to do any digital features!
If
the radio was flashed up to a "7BN" then it will be a standard xts2500
that will allow for 700 and all of the available flashcodes for that
particular model line.
However,
going by the model number on label as the radio, doesn’t necessarily
mean it’s not capable. If someone later updated the firmware/flashkey
to Host 07 or above, it will work
2.)
Second is must support a 9600 baud. If it supports this is will
obviously support digital, and the type needed for Brown County’s system
To determine this, as well as other features you need to look up the radio's flashcode"
http://www.radioreference.com/apps/flash/
Saturday, February 13, 2016
Poor Mans Tools
Way back shortly after I started blogging I pointed out some handy tools.
So what other tools can I recommend?
Well at one point in my past (prior to having access to a service monitor), I'd use the IF birdee of my scanner as a low power signal source to tuning 5 pole filters and the like. My old BC350 has a 10.85 MHF IF, so you subtract 10.85 MHz from the freq you need a carrier at, and voila a birdee. I think I measured it once and it was about -40 dBm. So when you need it weeker as you tune, you throw the scanner in the basement clothes dryer, or use a step attenuator on whatever you are working on.
Of course now days its pretty easy to use a Raspberry Pi to generate a narrow band modulated signal. IK1PLD has created some nice code for that that will easily let you transmit a 1000 KHz audio tone that you can create in audacity. His code even lets you adjust the power factor. This works nice up though the UHF bands.
I have that same old Bearcat scanner permanently fitted with a home brew deviation meter, which I wrote about before.
And of course with cheap RTL-SDR USB sticks you'll get a spectrum analyzer.
So what other tools can I recommend?
Well at one point in my past (prior to having access to a service monitor), I'd use the IF birdee of my scanner as a low power signal source to tuning 5 pole filters and the like. My old BC350 has a 10.85 MHF IF, so you subtract 10.85 MHz from the freq you need a carrier at, and voila a birdee. I think I measured it once and it was about -40 dBm. So when you need it weeker as you tune, you throw the scanner in the basement clothes dryer, or use a step attenuator on whatever you are working on.
Of course now days its pretty easy to use a Raspberry Pi to generate a narrow band modulated signal. IK1PLD has created some nice code for that that will easily let you transmit a 1000 KHz audio tone that you can create in audacity. His code even lets you adjust the power factor. This works nice up though the UHF bands.
I have that same old Bearcat scanner permanently fitted with a home brew deviation meter, which I wrote about before.
And of course with cheap RTL-SDR USB sticks you'll get a spectrum analyzer.
Friday, January 8, 2016
More understanding digital
A while back I referenced a couple Hak5 videos that talked about Pulse Code Modulation and Time Division Multiplexing.
It should be obvious by now that I feel we have pretty much reached a stone wall with conventional FM modulation. Carsons bandwith rule pretty much tells us we will always be limited in the amount of information we can carry using a traditional FM signal. It's time we amateurs look into and start experimenting with more modern OFDM and QAM modulation.
This is why I feel repeater coordination and the VHF and above band plans need some serious re-thinking. How are we evolving these to accommodate other modulation methods? If you recall VHF and UHF used to be dominated by AM till Wayne Green came along promoting FM. Well maybe its time for some change again?
It's 2015, and I feel for the most part the commercial networks are stable, and our role as hams for emergency communications as compared to the past is greatly diminished. I feel its time to focus on one of our other major basis and purpose pillars, to advance the radio art.
In this day and age its important to understand digital communications. I have been hoping that since the amateur license classes have been consolidated down to three that a new one would be introduced. The digital communicator license scheme of sorts. Hopefully I'll see this in my juncture in the hobby at some point.
Anyway let me introduce you to Claude Shannon. He founded information theory, which is the basis for all things digital. He is often called the father of the information age.
Information theory is pretty deep. I have yet to find a good watered down version of it for entry level hams. A number of years ago TAPR published a book titled "Wireless Digital Communications: Design and Theory," and this is probably as good as I have found.
John Stephenson, KD6OZH who passed away in 2014 was pioneering modern modulation techniques. Now we just need to carry the torch on.
PS; When you are done watching the Shannon video and doing your research homework on KD6OZH, you can view this DSP amd Nyquist video.
It should be obvious by now that I feel we have pretty much reached a stone wall with conventional FM modulation. Carsons bandwith rule pretty much tells us we will always be limited in the amount of information we can carry using a traditional FM signal. It's time we amateurs look into and start experimenting with more modern OFDM and QAM modulation.
This is why I feel repeater coordination and the VHF and above band plans need some serious re-thinking. How are we evolving these to accommodate other modulation methods? If you recall VHF and UHF used to be dominated by AM till Wayne Green came along promoting FM. Well maybe its time for some change again?
It's 2015, and I feel for the most part the commercial networks are stable, and our role as hams for emergency communications as compared to the past is greatly diminished. I feel its time to focus on one of our other major basis and purpose pillars, to advance the radio art.
In this day and age its important to understand digital communications. I have been hoping that since the amateur license classes have been consolidated down to three that a new one would be introduced. The digital communicator license scheme of sorts. Hopefully I'll see this in my juncture in the hobby at some point.
Anyway let me introduce you to Claude Shannon. He founded information theory, which is the basis for all things digital. He is often called the father of the information age.
Information theory is pretty deep. I have yet to find a good watered down version of it for entry level hams. A number of years ago TAPR published a book titled "Wireless Digital Communications: Design and Theory," and this is probably as good as I have found.
John Stephenson, KD6OZH who passed away in 2014 was pioneering modern modulation techniques. Now we just need to carry the torch on.
PS; When you are done watching the Shannon video and doing your research homework on KD6OZH, you can view this DSP amd Nyquist video.
Subscribe to:
Posts (Atom)