WRKC935

The CM108 is a very inexpensive replacement for the RTCM interface that is used for AllStar and the myGMRS linked repeater systems. Going into this, I will say that if you can't solder, are not computer savvy, and don't have some sort of test equipment, it will make doing this EXTREMELY hard to accomplish and you will fight with getting the audio at an acceptable level. The CM108 (which is actually the part number for the USB chip) is a USB audio interface with I/O (inputs and outputs) that can be used for connecting a radio to a Raspberry Pi. I am not going to go through all the soldering and wiring stuff since it's WELL documented on the web. I will tell you that you will need the PTT output and the COR input for interfacing to a system. While the speaker level output voltage is very close to what is needed to drive a LINE input on a radio (not a direct Microphone input) the Microphone INPUT will need a voltage divider network to get the output from basically ANY radio down to a level that it can process. I set the interfaces BOTH to a -10dBm level into a 600 ohm load on a TIMS set. And while a TIMS set is not 100% needed, it is MUCH easier to get a fixed level to start with before connecting the interface to a repeater for final adjustment. With a -10dBm signal being generated into the mike input, you will need a 20 to 1 voltage divider or a 50K pot on the input. The two resistors to use for a 20 to 1 divider would be a 20K ohm and a 1k ohm. The 1K resistor and the 20K resistor get wired in series. One end of the 1K resistor gets grounded and the floating end of the 20K resistor is fed the incoming audio. The connection point between the two resistors feeds the input of the CM108. This is fed from the RX audio from the repeater, it's best to just use unfiltered audio and allow the Pi and the CM108 to process the audio. For the TX audio, for the -10dBm I mentioned before the setting on the CM108 configuration is 990 in the simpleusb-tune-menu. Which I will get to in a minute. But that provides a good relative level to feed into a repeater. The repeater I interfaced to was an MTR2000. I did NOT use the wireline interface with the CM108 because true wireline is a balanced input, meaning there is no real ground and 'positive'. Like a twinlead antenna cable. The output of the CM108 is unbalanced, meaning it has a ground wire and a 'positive' wire that the audio rides on. connecting a balanced input or output to a balanced input or output WILL cause hum, noise and headaches that you will NEVER solve with your audio quality. The RTSM does have balanced outputs and WILL work with the wireline interface to a repeater. But if your repeater doesn't have a wireline input, it can also cause hum and other issues. So remember that all inputs and outputs need to be balanced or not, mixing them is NEVER a good idea. You can do it via impedance matching transformers, but that further complicates the build. SIMPLEUSB-TUNE-MENU and SIMPLEUSB.conf These are two files that are in the distribution for Asterisk that setup the actual CM108 interface. And they can bring you heartache and pain. The first issue that you will encounter is that the interface will not accept audio without BOTH a core input and a PL being received on the audio line. These settings are in the simpleusb.conf file in the /etc/asterisk directory. To edit the simpleusb.conf file you will log into the Pi and type 'sudo nano /etc/asterisk/simpleusb.conf . This should bring up a test file that willhave a number of different things in it. The parts that you are looking for are the 'rxboost = ', and the 'ctcssfrom = '. These need to be set to rxboost = 0 and ctcssfrom = no. The one that will give you headaches is the 'ctcssfrom=no' because it's set for 'ctcssfrom=usb' which means it REQUIRES the PL or CTCSS tone be present on the input audio line (receive audio). If you have filtered audio and not discriminator (flat) audio coming from the repeater, and have the CTCSS tone set elsewhere in the configuration of the Asterisk, it will NOT receive. Setting that to NO turns that function off and allows the 'carrierfrom =' setting to control the RX from the repeater into the interface. THIS IS REALLY IMPORTANT because it don't work if you don't change this. You are advised to use 2n2222 transistors to invert and isolate the inputs to the CM108. The information on doing this is again on the web in a number of places. But they will protect the interface board that can't deal with the 5 volt output from the repeater to the CM108 that should only ever see 3 volts input. These little interfaces will allow you to connect to many different repeaters besides Motorola units that have a wireline interface and will also also allow you to connect to an MTR repeater that doesn't have the wireline card installed in it. These are getting harder to come by since they haven't been made in a number of years. I am FAR from a guru on this. But i have worked on countless numbers of MTR's over the 15 years of being a two-way tech. Feel free to ask questions and I will do my level best to answer them. But there are others here that know FAR more than me about the Linux image and other parts of the myGMRS network of repeaters.

UPDATE. Repeater is on the air and linked. Had some issues to work out with the CM108 interface. But once I figured it out it went pretty smooth. Gonna do a write up on what needs to be set with using a CM108 and the config files for it and getting the audio coming out of a radio to a correct level fro the microphone input.

Yeah. there is a MUCH cheaper way to do EXACTLY what Bridgecomm is trying to see you, But you do it yourself. Couple requirements. First is you can solder, really small crap and I mean tiny. Second is you are sort of computer savvy. We aren't talking full on Guru, just understnd basic networking, hopefully some Linux and know what a Raspberry Pi is. You can take a couple Raspberry-pi units, and a couple CM108 devices which is a simple USB sound card with some I/O on it and basically build what you need for teh site equipment. Every bit of the information you need to do this, or at least MOST of it, is on the Internet. You are going to use a system called Asterisk, which is a VoIP phone system basically that will run on the two R-Pi units and communicate to each other via an IAX trunk that is created betweenthe two units on via the Internet or any network you have access to that is accessable from both sites. You will see mentioned on here about the different linked GMRS repeater systems that are talked about. They are doing basically the same thing on a much larger scale. If you aren't up to the challenge of learning this stuff, you can get some help,, you can buy some parts and you can still make this work for less money (a LOT less). The Raspberry Pi's can be replaced with small PC's running Linux and Asterisk, but you are gonna need to do some research and learn a few things to do this on the cheap. If you aren't able to commit the time and effort into this, then bite the bullet and buy the Bridgecom stuff, or similar equipment.

Now all that being said. GMRS and Ham licenses are BOTH going to be 35 dollars and last 10 years at this point. So the SAR / CERT groups that are pushing folks to get ham licenses could just as easily push their members to get a GMRS license that requires no testing. Ham radio is great for what it is. It's a fun hobby. The problem with ham radio and CERT / SAR operations is they typically want to rely on other peoples infrastructure. ANd that can work if that infrastructure is installed and maintained at a high level. Problem is that it's not always that way and it can become a single point of failure for communications. And I am not saying that a GMRS repeater is somehow more technologically advanced than a ham repeater, but if you as a group have a GMRS repeater, YOU as a group are going to be the ones maintaining it. And while this may 'hurt' ham radio if CERT / SAR folks go the route of GMRS, if that was their only motivation to get a ham license, then what were they bringing to ham radio to begin with?

For only TWICE what a used MTR2000 currently costs that is a FAR better machine. And I agree that the CCR's should be avoided for running back to back as a repeater. Which is why I specified the CDM radios that are available on ebay for under $100 each. Not sure you can even get new mobile CCR's for that money, and the CDM is a better radio than the CCR's. My point was you COULD build a decent DIY repeater for less that $500 all in from antenna to power supply if you were willing to figure a few things out. Learn to program a couple radios and could solder (if you wanted to interface to the system as a Node).

I got it working ... nevermind

Nevermind... He got it working and I missed him saying it.

UPDATE. I now have the interface connected to the system and it seems to be operational. I will be building the interface cable tomorrow evening and will be setting levels with the service monitor on Friday to get this done. I am not even good enough at Linux to call myself a noob. But the guy that owns the tower has been a Linux admin since 99 and has ALLStar nodes of a single 'thin client' running 4 Allstar interfaces so he was able to assist. I had created some additional hurdles for myself by locking down the firewall to the specific port needed to connect which wouldn't allow the software to download and install at all. Once I realized what was going on I opened up the traffic and it started running. It's not that I am worried about someone coming in the Pi from outside and getting back to the Internet,,, but I DO have other networks that are routable on the subnet that the Pi is on and those need secured, if for nothing else my own piece of mind. I will be working out the firewall config to block most traffic from the network the Pi is on back around to my other stuff. But, I am on and wil be on the air with it by Sunday I hope.

Had a question ask on facebook by a member about this very thing. Figured I would put it in here in detail for ALL to reference. Three levels. There are basically 3 levels of repeater system build out. The "system" refers to the radio equipment, controller if external, antenna, line and the duplexer. These are the building blocks to ALL repeaters. Eliminate any of this and you no longer have a repeater. So how do you decide what level you are building for? Easiest way to answer that is your antenna and it's height. If you are putting a an antenna under 50 feet then you are at level one. Now of course if you are on a mountain, that's not gonna be the case, but if you are in a town or city and the house and not a tower is supporting your antenna, or it's a small tower under 50 feet, your coverage for the most part is gonna be fairly local and you are NOT gonna have a ton of people using your repeater. Second level is a GOOD antenna that is over 50 feet on a tower or other tall structure. Third level is antenna's above 100 feet on a tower or other tall structure. And of course, antenna height and quality will determine how far your repeater talks and can hear. There are other factors, but height and gain are the two big determining factors. Levels of repeaters... First level is the little plastic box things that are two portables in a small box with a small duplexer in the box. These are the most basic entry level setups and are good for mobile and portable systems and small systems for your household to communicate with. Second is the DIY or "two radios in a box" repeater. the GR1225, GR500, XPR8300/8400 and a host of other commercially available solutions fall into this category. BUT YES you CAN build you're own repeater out of two radios and some sort of controller connecting the two together. Add a duplexer and antenna and you are off to the races. Which I make sound fairly easy,, and it actually is. And cheap too. You will need some sort of power supply as well to power the radios and controller but that's not hard to source. What radios? My choice for YEARS has been the CDM series radios from Motorola. They are reliable, CHEAP now and available on eBay. You will need to decypher the model number on what you are buying so you know that they will work on GMRS or HAM (for you ham guys) and the power output but those are the only considerations needed for selecting the right radio. They have a common connector on the back that makes interfacing them to a controller very easy. And in a pinch, they can be directly interfaced to each other with NO controller and will work as a repeater. There are other radios out there that are equally simple to interface, but you need to verify they have the connector to do the interfacing with. Kenwood for one had a number of radios that you had to buy an option cable to get the interfacing or open the radio and solder wires into it. This is NOT in the scope of this post and if you KNOW how to do that, why are you reading this to begin with? So, keep your life simple and buy a couple CDM750's and be done with the DIY radio part. Then you have a duplexer. This is an important part of a repeater system and cost range from 100 bucks or less for the small 'mobile' duplexers on the used market to thousands for a pass reject duplexer new in the box. For the smaller level one and two setups the mobile duplexer is fine. You can of course use a better duplexer but you aren't really going to see a performance gain from it until you get an antenna up in the air where it is going to start catching noise and co-channel RF that makes the expensive units shine. But the mobile units should never be considered on a tall tower or in an area with a lot of other RF present. Controller. Lots of options here. Starting with the Raspberry Pi and Arduino boards. Either will make a fine repeater controller with minimal cost. But you will need to learn some basic computer stuff to get them up and running. When you start looking at the ham and GMRS off the shelf controllers, the prices goes up a lot and you will be quickly getting to the point of the cost of a used 'two radios in a box" solutions.

I am getting the no channel type registered for "SimpleUSB' when I issue the 'asterisk -c command' AND I am getting unable to connect to remote Asterisk (does /var/run/asterisk.ctl exist' which it does. I am guessing the asterisk.ctl thing is a port I need to open yet on the firewall. But asterisk isn't running that I can find on my Pi and I'm not sure that the simpleusb thing isn't causing it to NOT run. Pls help

Update. Repeater is on the air. Fought the programming part. Dumb laptop had a busted screen and it was the only XP machine I had there with the software. SO I ended up connecting it to the service cart monitor. Not a big deal, just a pain. I have already heard someone on there doing radio checks. If you are in the area, it's there to be used, so use it but PLEASE remember to ID your station. Working on the linking to MidWest GMRS. I have the Pi loaded and I believe configured. I am working on the interface cable. I am using a common USB module that see's alot of use in All-Star on ham radio. There are some differences with it and due to that I have to look at other options for the audio interfacing. Wireline is the standard configuration, however wireline is a balanced audio path and the USB module in unbalanced input and output so I will need to interface the audio into the MTR via the 96 pin connector instead of using wireline. Crossing balanced and unbalanced stuff has always been a pain and typically requires isolation transformers (that technically make unbalanced into balanced audio) to not end up with any and all sorts of induced noise on the signal. I am NOT about to go through all this to have a crap noisy node on the system and my call sign attached to that. SO you're gonna have to bear with me so it can get done right. Other minor issue is firewall configuration. I am not seeing the node show up on the web site so I am unsure if it's connecting. Is there a way to tell from the Pi?

Will be cabling up and putting repeater number 3 at the site. This is Johnstown 625. This repeater will be connected to the MidWest GMRS wide area radio network at all times. We do have the Johnstown 675 and 725 on the air as well for local traffic. If you are in this area and want to experience a wide area connected system, this is your chance. Please realize this repeater will ALWAYS be connected to the wide area network. So if you are just wanting to talk across town, please use the 675 repeater for those communications.

I will be there as a vendor. If someone wants to designate a frequency and tone I can put it in the scan list and will monitor and say hello if I hear someone. Not sure what all I am dragging over there. May well be a a bunch of UHF XPR radios but not sure. Please post a frequency here so we can all program in in. I don't know of any open repeaters in that area, but someone might check the maps.

I vs N. First off N means Normal and I is for inverted. the DPL/DCSS/ or what ever they are calling it has two 'modes' one being normal the other being inverted. Not all radios support the Inverted DPL, but many do. From what I remember they did the inversion thing to double the number of DPL codes that could be used. If a repeater had just D245 and no I or mention of inverted, inversion, reverse I would say that is gonna be D245N in your radio. Easy way to find out is program two channels, one with the D245N the other with D245I and one should work. But as others have mentioned,,, don't be surprised if someone asks you to leave depending on where you found your information. If it's on THIS web site and it lists the repeater as OPEN it most likely is indeed open. If you found it on radio reference or some other scanner web site or similar, it may or may NOT be open. And this site doen't have every GMRS repeater listed on it. There are other GMRS sites and groups. Most should be welcoming to new members but they also may not be so friendly. There honestly no personality test for obtaining a license, I know this for sure because I got mine, and I would have failed that part miserably, just ask some of the members on here.

Right,,, anything in the commercial part 90 realm with F as the beginning of a station designator. FB = Fixed Base. A 'base station' would be a simplex Fixed Base running a single frequency (simplex) to another station. That station may be a portable or mobile. FB-2 is the designation for a 'shared' repeater frequency that is not being used without first verifying the repeater transmit frequency is clear and not in use be a co-channel licensee adjacent to your licensed operating area. These licenses can and are granted to multiple users in the SAME geographic area. THe use of PL and DPL coded squelch is used to limit the users from hearing each other BUT users are required (although it's RARELY done) to monitor the output frequency BEFORE transmitting to limit interference. Radio's operating under this type of license are programmed to monitor for any carrier that may be present and keep the user from transmitting until the carrier is gone. FB-6 designates you are the only user in the coverage area and the next user of that frequency does NOT overlap with your licensed operating area and you may use the frequency as a control channel or other use were it's NOT required to first monitor the frequency to see if it's in use before transmitting. Then you have FB-8 and Market frequencies. These are effectively OWNED frequencies for a large region. Paging companies used these for paging transmitters that would constantly bang away 24-7 and never stop transmitting. Market frequencies are typically not licensed as a single pair however, they are a frequency range in some instances that cover multiple 'pairs' of repeater frequencies. Paging would typically use the input frequencies as links and the outputs were what the pagers were listening for. So back to the Fixed base thing with GMRS. It would make little sense to limit the power between a mobile or portable and a fixed base but limiting the output power of a radio that was accessing a repeater with an elevated antenna (commercial limits BOTH power to a certain wattage and an antenna height to 20 feet above any obstruction specifically for radios that are communicating to a repeater and not directly to subscribers (mobiles and portables) so they are NOT interfering with other repeaters on the same frequency. But, I will also repeat that the FCC has not made it really clear on what a Fixed Base is specifically when it comes to GMRS. A repeater is technically a fixed base in the commercial realm, but that doesn't seem to apply to GMRS as you would need to limit a repeater to 15 watts if that were the case. So again, my vote is they are referring to a control station or a radio at a fixed location that is NOT in a vehicle or a portable radio that is directly communicating to a repeater. Now I am applying logic to this and the FCC is not logical at times. But it does make the most sense. That being said, a call to the nearest field office or an email to someone at the FCC may clear this all up. If someone is motivated enough to email or call them please report your findings back here. I may also ask them the next time I have need to call them on other non-related matters.

Fixed station VS base station. Gonna assume that fixed station MAY mean control station where a base radio installation is being used to communicate to a repeater. Commercial radio refer to that as a control station and they are limited in both power and antenna height.

Welp, I stand corrected. But that knowledge does make thing easier. You can have a cache of FRS radios that can be handed to anyone and you can then have short distance communications with them radio to radio... I would assume that they can't use FRS radios to talk on a repeater.

Not sure if this was specifically said,, so if it was, I am repeating it. If you are communicating with an FRS user that is using an FRS radio and is unlicensed then YOU are using that service. Since you are using that service and NOT GMRS which is licensed then YOUR radio needs to comply with the service it's being used on. GMRS and commercial radios are NOT compliant with the rules of FRS and therefore can't really be used to communicate on that service even if the frequencies are the same. Would you get dinged for doing it, PROBABLY not. Unless there were other factors involved. But if the FCC really wanted to they could fine you and pull your license.

It probably would sell.... but the rules state it has to be of a certain design that would not lend itself to being a mobile radio. The big thing the FCC was trying to limit was the ERP or effective radiated power. The antenna's on FRS radios are very low gain by design. Making them permanently attached means they can't be swapped out for a high gain antenna and it also means that an amplifier can't be put in the line increasing the power. With the new license fee schedule making GMRS licenses $35 for a family unit, it's really just easier to have everyone that you want to communicate with get the license and get out from under the FRS equipment limitations. You still have some limitations with GMRS, like max of 50 watts at the radio output and no additional amplification.... but the antenna gain and height are not restricted at all. Even on the low power channels. And you just don't bother with the low power channels other than walkie to walkie short range stuff were it's all you need. FRS is still good for certain applications but it's not technically legal to use a GMRS radio to even communicate to an FRS radio even though the channels overlap. If you are talking to an FRS radio then BOTH radios are using that service. And then both radios need to be compliant with the FRS rules. So you CAN'T use your HT1250 that you use for GMRS while talking to an FRS bubble pack radio.

I have been working on this very thing for the site. What I have figured out so far is that for any significant solar / wind backup system you either need to be able to build it yourself or you need really deep pockets if you are going to backup much at all. Off the shelf stuff is really expensive when you get to the point you are trying to generate more than a few hundred watts and anything wind related is costly no matter what. The first thing you need to realize is that a grid tied charging system is NOT a bad thing if you are going to have any sort of large battery plant. A large plant doesn't need to be off-grid unless there is a specific reason, like there is NO grid at that location. Those are special circumstances and I am looking to do that. Another important part is plant voltage. Lots of guys are building 12 volt plants, and while that's OK to a point. If you need MORE voltage to run certain gear then upping the voltage requires equipment that is not efficient in the line. Stepping 48 volts DOWN to 12 or 24 however is much easier and more efficient. I am looking at panels and a DIY 55 gallon plastic barrel wind setup that will charge the 48 volt plant and provide constant power for several repeaters and networking equipment. The repeaters are 12 and 24 volts in and the networking gear is 48. It's a good idea to find equipment that needs to on power supplies that power off 48 volts. That stuff is out there, although it's a bit more expensive than the 110 volt gear. Cisco made routers, switches and firewalls with 48 volt input supplies that fill this bill and much of the microwave and WiFi linking hardware from various manufactures is 48 volt and use a wall wart power supply to derive that from line voltage. That part just gets eliminated and you feed the plant power directly to the device. Another thing to consider when grid tied is load shedding when you loose the grid power. Meaning if you have 6 repeaters that are running from the plant and one 2 of them are truly critical to ongoing operations, you need to cut power to the other 4 repeaters to minimize the load. A LOT of this is planning and design before you just start hooking stuff up. And depending on what heat load you site has, you need to consider what you are going to do to remove heat from the facility when the grid is down and you have no climate control in the building. Part of your planning is load calculation. I will say that if you are planning to keep one radio and a cell phone charger running, all this is pointless. But if you are backing up significant equipment the calculations are critical. And it need to be based on a 24 hour period and not for one hour or instant load. Instant load being right now, I am drawing 2 amps, but not everything it running, transmitting or what ever. But it also means that you don't need to build to max possible current draw 24/7 for battery and charge capacity. In a 24 hour period, you will have change time and discharge time. You need to figure out How much charge will be needed in that window of time to bring your batteries to have enough stored energy to get through the discharge window and not be depleted before the next charge window. And that may need to be figured on a discharge window of MORE than 24 hours. And you need to consider that may be up to 36 hours depending on where you are, how much sun you get and how much wind you have when the sun isn't shining. Point is that there CAN be a lot that goes into building a reliable 'mission critical' solar / wind battery plant. If you are looking at a small load, then a 100 watt panel and a couple batteries is fine. If you are wanting to be able to run off-grid for an extended period, then you are gonna spend time and money to get to that point but it IS achievable with proper planning and finance.

If they were using anything outside of FRS without IDing their station then no, they were not operating within the law. HAM requires you ID every 10 minutes. Other services the timing is different but they all still require that you ID. That would apply to any licensed service. FRS and CB do not require or have a license, and therefore you can't technically ID because no call sign is issued to be used for that purpose.

Using Mister would mean the use of some level of respect. So that obviously ain't happening. And that's how many times you have spelled my name wrong? And then EXPECT me to show YOU respect. You're attempts at being a comedian here are coming up short. I guess as long as you think it's funny in your mind then at least someone is amused.

Wow dude, you're hilarious. My guess is that it wouldn't start with KB8 since that's MY call sign. Do you really think that's funny???? Or is this yet another attempt to bump your post count or just to see if you can get a rise out of someone? I am thinking that you specifically said a while back you were gonna NOT reply to my posts and stay in your lane. What happened with that? Decided that you needed to entertain yourself again and try to screw with me? I suppose that everyone needs a hobby.

Rules on a Club call still require a club member with a valid ham license to act as a control operator for all transmissions. Meaning someone with a ham license needs to be present when people are talking on the radio using the club call. So the bigger question is what is the call sign you speak of? Assuming it's a call ending in BSA. Once you know what the call is you can look it up. The call will be linked to whoever originally applied for it, or at least who the trustee of the call is now. SO, it can only be one of a few calls to be a valid callsign. Hams of course will know that it has to begin with a K N A or W. At least if it's an American call sign. I don't believe that ham calls can start with anything else. It will also have a 0-9 in it and it will be a single digit followed by the B S A letters. But ham calls have to follow a pattern that the FCC set down long ago. You could do a partial call sign search on the FCC web site or possibly QRZ to find the call and then look it up on the FCC web site and see if it's an individual call or a club call. Once you do that you will know for sure. If you have a troop and want to use the call I would assume that you could contact your district office or the national office once you find the name of the individuals that are the trustee's or just contact them directly in order to gain permission. I would NOT advise you just use the call sign without first getting the OK from the trustee's however. And of course if it's an individual call, you can't get permission to use it without them being present during your operations.

Yep,,, this is a good reason to not post at night. You don't see everything you need to, say something wrong and Micheal gets to up his post count.