Lscott

It's not so "simple" when people regularly propose to use their favorite channel for the "official" travel channel. It's useless to a new GMRS user who reads in one place that channel xx is the travel channel, then later somebody else says it's channel yy, then even later another claims we should all be using channel zz because it's what some other radio service uses. Just thank GOD we only have 22 channels so the confusion is somewhat limited. Maybe the government can step in and mandate channel usage like Australia has done with their license free UHF CB radio service. They have 80 channels. https://summerstar.com.au/blog/uhf-channels-australia

If you can't afford $70 for a license good for ten years you likely can't afford to buy a radio to use the license either.

Seems like regularly somebody wants to advocate for their favorite channel to use as a travel channel. Just program all 22 in, scan them all and be done with it. Then it won't matter.

And the best part they manufacture themselves, no chip shortages or high gas prices to worry about. The waste products are naturally recyclable. When the bombs fly and the big EMP event they will still keep working too.

I'm running Firefox on Linux, OpenSuse, and when I click on the link it asks if I want to use Libreoffice to open the file. I have that package installed so it works for me.

Yup. All valid points. The old stuff gets used because it was cheap, like saved from the e-waste guys for free, and recycled. Hams are cheap. I guess that's why many own a Baofeng too. Oh well.

Depending on the vintage of the equipment yes it may have to be hacked. Some of the older Part 90 stuff has to be "re-crystaled" and re-tuned to work outside of the original specifications. Yeah there is some REALLY OLD Part 90 junk out there that should be in a land fill being used on the Ham bands. There are all sorts of things that can go wrong, a few you might not have considered. One nasty type is caused by mixing in the output stage of a transmitter caused by signals getting in through the antenna port. The transmitter looks great on the bench with a spectrum analyzer and dummy load until it's installed on site in close proximity to other high power transmitters then the problems crop up. https://www.softwright.com/faq/support/intermod_finding_solving.html I in noway inferred the Black SUV will be rolling out. My comment is simply Ham built systems have a bad reputation with some people, justified or not. Some site owners will not allow Ham equipment just so as not to piss off their paying customers. Hams are basically cheap and look for no rent locations. Some even get free electricity and network access. A buddy at my Thursday night coffee group has one at a local school. He's not paying a cent for his UHF repeater with free power, including backup and Internet access. So, if a site owner can use the objection from his paying customers over a Ham system, who are likely paying basically nothing, and sell the space to somebody else for good money that's all the motivation they might need to reject the Ham equipment. Is that fair? But that's business.

I've heard stories where Hams can't get their equipment colocated with commercial equipment on building roof tops and towers because the commercial guys don't want to waste their time trying to trouble shoot issues with their equipment caused by poorly maintained or modified Part 90 stuff to get it on the Ham bands. They have a business to run and people pay good money for the service(s) they provide.

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-(