6
votes
Accepted
How are secret encodings not a violation of amateur radio regulations?
My understanding is that the AMBE voice codec used by D-STAR, System Fusion, and DMR is secret.
That is mostly incorrect. The IMBE/AMBE+2 codec is standardized and documented as part of P25. The same ...
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4
votes
How are secret encodings not a violation of amateur radio regulations?
First, thank you for asking this question, it's a fun one to explore!
Is that a documented ruling by the FCC?
I haven't found any documented ruling by the FCC on your question... but I believe your ...
- 4,658
4
votes
Accepted
Modulation details of Digital Mobile Radio (DMR)
ETSI TS 102 361-1 Clause 10 is pretty explicit on that:
10.1.2 RF carrier bandwidth
The radio system operates within a 12,5 kHz RF carrier bandwidth.
…
10.2.1 Symbols
The modulation sends 4 800 ...
- 17.4k
4
votes
Accepted
A new ham should start with Digital or Analog Portable Radio?
I would suggest Analog FM only, to start with.
Most repeaters are still FM, you won't be missing out on any coverage if you don't have digital.
The digital landscape is still a bit fragmented, with ...
- 12.2k
2
votes
Digital Modes Transmission Traffic Comparisons
I think this is an interesting question, but seems hard to answer. In the USA, perhaps you could FOIA the FCC to see what their monitoring stations cover and/or if they collect any data on this.
...
- 7,469
2
votes
Help with ZaStone D900
To answer each point in turn:
DMR radios are different from "normal" ham radio equipment in that it uses a digital voice encoder/decoder rather than the more traditional FM analog voice mode that you'...
- 121
2
votes
Accepted
DMR code plug for Anytone d878uv
I did a web search for "new york code plugs" and found a bunch from various sites:
N2CID Digital Repeater Network
Hudson Valley Digital Network no Anytone plugs yet
BridgeCom Systems
I ...
- 9,320
2
votes
DMR Physical RF connectivity
I think you're looking for a splitter/combiner that will accept the feed-lines from both yagis on one end, and the feed line from your duplexer on the other end.
You'll need to be very intentional ...
- 4,658
2
votes
DMR Repeated Audio Packets
Repeating the last frame to fill in holes from missing frames is a common digital voice technique. For small rates of frame loss, repeating a frame now and then is less noticeable than silence.
- 52.5k
2
votes
Accepted
Is roaming strictly a DMR feature or does it also relate to analog?
This handheld radio requires you program in all the repeaters you want to use, so it already knows what is available and could, in theory, check GPS or it could check to see if there's a usable signal ...
- 17.4k
1
vote
Is roaming strictly a DMR feature or does it also relate to analog?
The radio can be programmed for DMR operation, or for standard analog repeater (or analog simplex) transmissions; you do not gain any DMR features while using analog.
- 59
1
vote
Accepted
Excessive frequency deviation for DMR handsets?
Verification through simulation of a DMR burst shows that the excessive frequency deviation is caused by the overshoot from the pulse shape filter ($\alpha$=0.20). The DMR modulator uses a RRC at the ...
- 151
1
vote
Excessive frequency deviation for DMR handsets?
Is it expected that low cost handsets have excessive frequency deviation?
No. Such a transmitter wouldn't work with standards-compliant receivers. Most symbol decisions would end up being wrong, ...
- 17.4k
1
vote
Repeater Amplifiers DMR vs Analog
So... really what you want to shoot for with a digital system is relative signal consistency between among the 1's and the 0's. With that in mind, recall that:
Class A amps are pretty linear, ...
- 4,658
1
vote
Brandmeister API - How to get the Last Heard from the API
Stephan from BM responded with the API does not provide last heard.
- 121
1
vote
Can the AT-D878UV be programmed for dPMR channels?
I'm tempted to believe that using dual time slots (DCDM) mode might work with dPMR, since you are no longer bothering with TDMA. However, I couldn't find anything in my research. Try switching the AT-...
- 143
1
vote
Did I enter my digital ID in Hytera PD785G?
The easiest way is if you send a private call to 9990 (parrot) in brandmaister network and see the actual traffic on brandmaister's site.
- 134
1
vote
Help with ZaStone D900
The radio you received is a UHF DMR HT. If you have a DMR repeater in your area, you will be able to do some testing of the radio. You can locate a repeater by visiting RepeaterBook.
The first step ...
- 18.6k
1
vote
Blocking a specfic DMR ID
I don't know any radio firmware that would support blocking a specific ID.
It would be easy to implement in MMDMHost.
Call Alert is a ringer function. If a radio receives a call alert signal then it ...
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