Lscott

That's flat out wrong. You have to be very careful reading posts on the 'net. There is a LOT of old and outdated information to be found. For example I still read posts out there claiming FRS is limited to 1/2 watt, which it hasn't been on most of the channels, on 1-7 and 15-22 it's now 2 watts, since around 2018. The few main things with GMRS repeaters are: 1. You observe the power limits set by the FCC on the repeater channels. 2. You operate your repeater(s) on the FCC list of frequencies reserved for repeater operation. 3. You use only the approved types of emissions, typically normal FM, and so have used narrow FM, in the transmitter section. 4. If there is any interference with other repeaters YOU and the other repeater owner(s), NOT the FCC, have to work out a solution to eliminate it. About number 3 above this subject comes up often enough with people new to GMRS. NO digital voice modes of any kind are permitted. Yes it would be nice if the FCC would just let people use DMR, which seems to be the favorite mode if it was allowed. Maybe at some point the FCC will change their mind, but so far the answer is a big fat NO when it's brought up with them for consideration. But, hey, they finally gave in to allowing FM on 11 meter CB recently, after some decades, so who knows.

I have some of those. They are OK except I don't like the muffled sound on the earphone. The coiled plastic tube seems to filter out a lot of the higher frequencies in the human voice. I much prefer the type below. This particular one the ear hanger is adjustable. The cheaper ones don't. https://www.maxtop.com/products/AEH2000-K2 The other advantage is since there is nothing that sticks in your ear it's far more comfortable to wear for long periods. I found the ones where you have to insert something in your ear channel tends to hurt after a while. I ordered one for the multi pin Kenwood radios I have from a seller on eBay. It was a bit more expensive than the non adjust models I currently have.

Good. Have fun.?

What is the final application for this?

If anybody has the interest there is some info in this PDF on digital modulation. https://ee.eng.usm.my/eeacad/mandeep/EEE436/CHAPTER2.pdf

Yes it has, but for me still very interesting and useful. I’ll have to did through some books I have in my personal engineering library to see what I’ve got on digital modulation methods. It’s got my interest up a bit. One never quits learning until you’re dead.

Well for at least NXDN Q4FSK the technical docs have the following. Now the screwy part is for analog voice we talk about just the “Deviation” nothing about positive or negative. Now am I correct in thinking the frequency out of the demodulator is one of those in the table. It’s not a pure carrier frequency shift. But when they show a negative frequency it’s the same FM modulation but the demodulated frequency is reversed in phase compared to the positive one. That makes more sense to me. If so that might explain why some have claimed success sending digital through an analog repeater. It does impose some tough requirements on the phase response of the audio circuits. I know human hearing is not sensitive to phase from what I read some time back so the designers likely wouldn’t care about it in the audio path in the radio.

I believe D-Star uses the AMBE while DMR, P25, and NXDN uses the AMBE2+ vocoder. At lest that's what the brochures for the radios I have claim. The dPMR format popular in Europe I've seen has used several different vocoders while the cheap Chinese radios that claim to be dPMR used something like AMBE2+C which, apparently, is really ASLEP, or ACELP. https://radiosification.blogspot.com/2018/02/aselp-vocoder.html I also know one of the major problems with AMBE type vocoders is background noise. It seriously mucks up the algorithms used to extract the model parameters. The manufactures mostly fixed that by including various types of signal filtering on the analog audio signal in the radio. With NXDN used by the railroads I read a lot of the older equipment is controlled using DTMF tones which the vocoder doesn't handle well to the point where they revert back to analog FM in those cases. I've also been looking at the idea, where as you pointed out, connecting radio's discriminator output to the other radio's modulator input. I'm not sure that really works so well if at all. If it does I would like to see a good explanation why it does. The Q4FSK modulation used by many digital formats requires the carrier frequency be shifted a couple of steps above and a couple below the unmodulated carrier frequency for a total 4 possible "discrete" frequencies. However with FM audio, applied to a modulator, results in a frequency deviation above AND below the carrier, not the step change above or below the carrier depending on the data you see with digital. The frequency deviation depends on the signal amplitude while the harmonics present depends on the frequency content of the audio.

There has been some discussions of a cross-band digital repeater. Sort of buying one purpose built that leaves rolling your own. The easiest one is to cross couple two radios together using the microphone and speaker ports, with the necessary signal level conditioning. Some discussions on other boards seems to suggest trying to run digital through an analog repeater most likely won't work. However some have claimed they did manage to get it to work, sort of with certain types of digital voice modes. In a real digital repeater the signal is not decoded to audio, just pure digital data, and then fed to the digital transmitter. The vocoder is not really used so no signal quality issues due to the conversion between analog audio and digital should be present. The only "analog" repeater that has any chance of passing a pure digital signal I've run across is called a "linear translator", or "linear transponder". Since the signal is not converted to audio there should be no issue. http://www.amalgamate2000.com/radio-hobbies/radio/dunedin linear.htm http://www.amalgamate2000.com/radio-hobbies/radio/Rotorualinear.htm The idea I'm thinking about implies transmitting to the repeater, with a digital radio as the receiver, decoded to analog audio, coupled to another digital radio to re transmitted in digital. The vocoder that is most likely to be found in the radio is the AMBE2+ from DVI. These vocoders do not digitize the voice but extracts the elements of speech the human ear recognizes as intelligence and transmits just that as a set of vocal track "model parameters". On reception the vocoder uses the info to "simulate" a human vocal tack to reproduce human speech. The question is has anybody had any experience with using two vocoders in cascade? Since the second vocoder is not really trying to model real human speech I'm wondering just how much the quality degrades doing this?

That's an Microsoft Exell spreadsheet. If you don't have their office package you can install a free open source office suit from these guys. There are versions for Windows, Linux and MacOS. It does pretty much everything MS Office does. It can be setup to open and save files in their office pack formats too. https://www.libreoffice.org/ https://www.libreoffice.org/download/download/

For KPG-49D check the listing here: http://rsws.zapto.org/radiosoftware/Kenwood/ Spreadsheet for radio programming packages for radios: https://radiosoftware.online/KENWOOD/SOFTWARE/!!!KENWOOD Current Versions - 2017.xlsx

I'm a Kenwood guy, but I'm sitting this one out.

Larger diameter wire/tube tends to increase the bandwidth of the antenna. That's why when you look at a disk-cone commonly used for scanner applications the vertical element has a bunch of wires to increase the bandwidth so its a better match to the feed line. On a simple 1/4 wave ground plane at mid to high VHF and low UHF 3 to 4 ground radials is usually enough. Adding more won't make much difference. I built a simple 1/4 ground plane, 4 wire radials, out of a BNC socket and 1/16 inch buss wire. I got a 2:1 SWR bandwidth from 430 MHz to 470 MHz after tweaking the element lengths a bit and radial down angle. Looks sort of dumb but works good enough when I went to the Dayton Hamvention a couple of years.Hattenna UHF SWR Scan Results.pdfHattenna UHF SWR Scan Results.pdf If you want to get into modeling software for antennas try looking at this package. The guy has retired and doesn't feel like providing further support so he just made it license free to use. I've used it a bit on and off since V3. It does a good job in most cases. https://www.eznec.com/

Yeah, a nice cleaned used Bird wattmeter is next on my list of toys to get. Then I start saving up for that spectrum analyzer…..

Even experienced engineers forget at times test equipment can lie, and very convincingly too. The best test gear you own is your head, use experience and common sense.

I'm surprised the house keeping department at a close by mall has been operating without a license on GMRS, they have a repeater so there is no question they aren't operating under FRS rules, since 10/2015. It was never renewed from what I can see. If you look under the "ADMIN" tab in section "Special Conditions" you can see the repeater channel they were licensed to use at the time. I hear them on the radio at times, also the mall security has used it to contact the house keeping staff as well. FRN: 0002748242 Callsign: KAB1523 https://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=194751 https://wireless2.fcc.gov/UlsApp/UlsSearch/licenseAdminSum.jsp?licKey=194751 I wouldn't be shocked if there are other cases like this around the area.

No kidding. Except for a nice mobile I got for free everything else I had to pay for. 8-(

I have a subscription to QEX which is their tech publication. The articles are several levels above what you see in QST. When the ARRL sends out a request for funds to cover their efforts on spectrum issues I try to send them a few bucks. It's worth it. I don't think most people understand how many and how often the Ham bands are being targeted by commercial interests. That's how we lost part of the 1.25M band. As it is Ham are SECONDARY users on the 70cm band in the US. In various countries Hams only have 430 MHz to 440 MHz. From Wikipedia: U.S. reallocation In 1973, the FCC considered Docket Number 19759, which was a proposal to establish a Class E Citizen's band service at 224 MHz. The proposal was opposed by the ARRL and after the explosive growth of 27 MHz Citizen's Band usage, the FCC dropped consideration of the docket in 1977.[9] In the late 1980s, United Parcel Service (UPS) began lobbying the FCC to reallocate part of the 1.25-meter band to the Land Mobile Service. UPS had publicized plans to use the band to develop a narrow-bandwidth wireless voice and data network using a mode called ACSSB (amplitude-companded single sideband). UPS's main argument for the reallocation was that amateur use of the band was very sparse and that the public interest would be better served by reallocating part of the band to a service that would put it to good use.[10] In 1988, over the objections of the amateur radio community, the FCC adopted the 220 MHz Allocation Order, which reallocated 220–222 MHz to private and federal government land-mobile use while leaving 222–225 MHz exclusively for amateur use.[citation needed] The reallocation proceeding took so long, however, that UPS eventually pursued other means of meeting its communications needs. UPS entered into agreements with GTE, McCall, Southwestern Bell, and Pac-Tel to use cellular telephone frequencies to build a wireless data network.[citation needed] With the 220–222 MHz band then left unused, the FCC issued parts of the band to other private commercial interests via a lottery in hopes that it would spark development of super-narrowband technologies, which would help them gain acceptance in the marketplace.[citation needed] In the 1990s and into the 2000s paging companies made use of the 1.25-meter band. Most all such use ended by the mid-2000s, with the paging companies being purchased by others and services moved to newer systems, or having gone out of business.[citation needed] Then there was this garbage recently with the 2M band. http://www.arrl.org/news/restraint-urged-in-response-to-2-meter-reallocation-proposal

I'll bet it was interesting.

You can take a look at this one. It’s specifically for GMRS. https://www.arcantenna.com/products/gmrs-mobile-vehicular-antenna-base-loaded-chrome-coil-rugged-no-ground-plane-required-with-spring-rbc-450-5-ns With no ground plane required you can use it just about anywhere. Some of the dual band J-pole like antennas are another possibility for backpacking. Again no ground plane required. These you can hang on a string in a tree or zip tie to a fiberglass pole on your backpack frame. Also being dual band you can use either your GMRS or MURS radio with it. https://www.ebay.com/itm/222236729087

That sort of depends on your definition of hand held. There are people that go hiking or bike riding with a small back pack. In the backpack is a small battery, sometimes a small amp, with an antenna mounted on the backpack frame. The antenna is a no ground plane design. The user just runs a short jumper cable from the radio’s antenna port to the backpack. While this is for Ham radio many of the ideas could be applied to GMRS. https://mqc.beepworld.it/apps/download?f=%2FDOC%2FBiblioteca%2FWA3WSJ_s_PM_Handbook.pdf You might want to do some searching for bicycle mobile too. I’ve seen some very clever setups for using a hand held radio on a bike with a good mobile antenna etc.

Windows has a remote feature, Remote Desktop, where you can login remotely from another computer. At the point it's like sitting at the other computer's keyboard, screen and mouse. The remote computer uses Windows terminal services client. https://support.microsoft.com/en-us/windows/how-to-use-remote-desktop-5fe128d5-8fb1-7a23-3b8a-41e636865e8c I do this all the time at work. I have a Linux VM running on another computer with RDP, Linux's remote desktop service like Windows, and access it remotely over the company's network with Windows terminal services client software.

That's right up there with people building cross-band repeaters between MURS and FRS. Then use a cheap Baofeng to transmit through it since it is a dual band radio. Likely the cross-band repeater was built using Baofengs with cross over cables, cheap duplexer and dual band antenna too.

I got several of the VHF XPR-6550's and the low split UHF versions for Ham and GMRS. No hex editing required. When purchasing these off eBay i check the FCC ID to make sure which band split the radios really are first. Sometimes the seller doesn't know or spec's the wrong one in the description. The thing that is inconvenient is the 16 channel per zone limitation and just one 16 channel scan zone. I had to reorganize how I programed the radios compared to everything else I have to avoid the 16 channel limit. I did discover one thing about the radios hardware wise. The SMA antennas are slightly different from what you commonly see. While my Kenwood antennas, reverse SMA like the Chinese radios, screw into the radios they don't work. Looking at the bottom of the screw connector the official Motorola ones the center pin is flush with the edge of the screw barrel. The Kenwood's are recessed a bit so the center female pin doesn't make contact with the male pin in the radio. I had to buy some Motorola specific antennas and checked the connector on the bottom in the photos to be sure they would work before paying.

I’ve been doing some research looking into some very rarely used digital voice modes. One that has my interest peaked is dPMR. So far it seems it’s an European thing. It’s very closely related to NXDN, uses the same RT modulation, the the CAI, common air interface, is different. I don’t see any mention of it being used in the US commercially or by amateurs. https://en.wikipedia.org/wiki/Digital_private_mobile_radio https://kenwoodcommunications.co.uk/files/file/comms/uk/pmr446/PMR446-White-Paper-V6_18AUG2016_JT_KB.pdf Apparently at least one model series of Kenwood radios can be modified to use it. See link to brochure, first page in the middle on the right side. I’m not sure if it’s limited to just the”E” versions or not. https://www.azqartelecom.az/pdf/p1_3_1.pdf The software to enable it I discovered is KPG-97FW. The few European radio dealers I’ve contacted haven’t replied and Kenwood support in the US hasn’t been helpful on this topic either. I’ve only found one site that has it, Russian of course, but you either have to pay them a bunch of money for access to their collection of radio software, it’s very extensive, or contribute stuff they don’t already have, which isn’t much. So does anybody have any experience with dPMR and the above software/hardware?