Radioddity GD-77 frequency question

[Astro_Spectra]

You can easily figure if your wanted frequency is going to work by dividing it by 5 or 6.25 kHz. If the remainder is zero then it will work. Example:

154.3775 MHz is the same as 154377.5 kHz so dividing that by 5 giver 30875.5 so that's not going to work. You could tell before starting because writing the frequency in kilohertz immediate shows the 0.5 and an even 5 ain't going to fit that.

Let's try 6.25 kHz:

154377.5 kHz divided by 6.25 gives 24700.4 so that's not going to work either.

So the radio changed it to 154375 kHz which is divisible by 5 (and also by 6.25 kHz as it happens). But that's going to sound distorted on narrow FM and probably wont work on DMR.

Since the radio is intended for amateur use it may not have the right synthesizer design to deliver steps of 2.5 kHz. Some US frequencies, particularly at VHF, are a strange legacy of the old 120, 60, 30, and 15 kHz bandwidth channels that have been used over the history of FM operation. Most of the rest of the world used 50, 25, and now 12.5 kHz bandwidth channels and the needed step size is usually equal to half the channel size.

 

[Astro_Spectra]

1750 Hz operation still required for some repeaters in Germany last time I was there.

This is now available in the V2.6.1 firmware update.

 

[mbee]

This is now available in the V2.6.1 firmware update.

Hi!

I have looked at radioddity:s homepage and facebook page and have not found that firmware version.
Do you have a link to that firmware version?

regards,

 

[Astro_Spectra]

https://www.facebook.com/groups/789727154519141/files/

 

[mbee]

https://www.facebook.com/groups/789727154519141/files/

Thanks!

This firmware brought us monitor mode quicker than their facebook page suggests. It seems to work fine.

regards,

 

[Astro_Spectra]

The GD-77 gets better and better. Latest CPS is now V1.1.6 available from the link I posted above. When used with the latest software the radio will now support 5 kHz and 6.2 5 kHz steps.

The problem I have ran into is that on some frequencies that I put in it, such as 154.3775 ...

Unfortunately as I explained in post #22 your problem frequencies would need a 2.5 kHz step size. While the new CPS is a good step forward it won't solve your problem.

 

[TheBoz]

The GD-77 gets better and better. Latest CPS is now V1.1.6 available from the link I posted above. When used with the latest software the radio will now support 5 kHz and 6.2 5 kHz steps.



Unfortunately as I explained in post #22 your problem frequencies would need a 2.5 kHz step size. While the new CPS is a good step forward it won't solve your problem.

Thanks for the info and the updates, much appreciated.

 

[paulears]

Is the problem here not so much the actual steps, but the offset from the usual channelisation we use, I'm guessing a bit like DMR446 using FDMA, where two channels are popped into a 12.5KHz channel, but have to be offset either side of the centre of that channel, and that causes these weird frequencies. Radios not intended for putting on the DMR446 channels need these offsets, but often can't have them, as the programming software asks the channel width, and then the specific frequency, and they need the fine adjustment away from centre channel. No doubt these limitations will be lifted at some point when people complain enough.

 

[jonwienke]

I don't see the point of supporting FDMA frequencies on a TDMA radio. The channel width is still 12.5KHz even if the center freq is on an oddball 2.5KHz step.

 

[paulears]

I tend to agree, but I suppose it's because some people wish to use them in places where they really shouldn't, so one of these in the FDMA allocation would really be best hogging the usual centre channel, and wiping out two of the extra narrow ones? I suppose the reality is that with accuracy of frequency not really an issue, you can make them work on almost any oddball frequency.

 

[jonwienke]

If the channels are allocated for FDMA, then you shouldn't be using TDMA anyway.

 

[paulears]

Well, you shouldn't be using the radio at all, really!

 

[Astro_Spectra]

I think this has gone a bit off topic. The OP asked about receiving DMR on a widely used (in the USA) frequency from the Part 90 conventional public safety pool. Transmitting was not discussed.

The issues is the synthesizer step size in the GD-77 need to reach some FCC frequencies, the example the OP gave was 154.3775 MHz.

Turns out this radio uses the RDA Microelectronics RDA1846S transceiver chip. Looking at the programming guide it appears to support 125 Hz synthesizer steps. If this is correct, then there is potential for the needed 2.5 kHz steps size to be implemented in a future software release. It would be up to RO to release CPS support for that.

 

[TheBoz]

Just an update, with the last firmware 2.6.6 and software 1.1.8 update, the Radioddity GD 77 will take the frequencies that I could not get to program into it and it seems to be receiving very good on the digital and analog channels.

 

[Astro_Spectra]

There ya go.

 

[K8JLW]

Lee, just wondering if you have put your code plug together? I just got my GD-77 yesterday and am trying to get up to speed on DMR.

Reid, K8JLW

I have one on order , did they E-mail you when it was shipped? I have yet to get one, I also have to be the one that makes the code plug for VA myself as No one else has the radio around here,, I am curious as to what you come up with also being this radio is new,, Radioditty has a FB page,, it is hit and miss if you ask a question, I don't think English is a strong subject there

Sent from my VS995 using Tapatalk

 

[landlubber]

Talkgroup question

I realize that on Ham versions of the GD-77 or any DMR radio, that you can only use a talk group number once in your contact list, but what about commercial use where you have more than 1 user with a talk group number that is the same. For example some fire departments and maybe a public works dept. will use the talk group number 1, and the radio will not accept that number a second time.

 

[Drumbum]

I realize that on Ham versions of the GD-77 or any DMR radio, that you can only use a talk group number once in your contact list, but what about commercial use where you have more than 1 user with a talk group number that is the same. For example some fire departments and maybe a public works dept. will use the talk group number 1, and the radio will not accept that number a second time.

I don't believe I understand your question, infinity can use the same ID # just not at the exact same time, one person can talk on slot one and one on slot 2 at the same time,, maybe your talking about a connect plus or capacity plus DMR trunking system, this radio is not designed for,, hope that answers your question,

Sent from my VS995 using Tapatalk

 

[jonwienke]

You're confusing the number of users who can use a talkgroup, vs the number of group contacts that can have the same ID. IDs in a contact list must be unique, or the radio will not be able to determine which contact entry is actually associated with the ID. But that doesn't prevent multiple users from talking on the same talkgroup.

 

[N4GIX]

I realize that on Ham versions of the GD-77 or any DMR radio, that you can only use a talk group number once in your contact list, but what about commercial use where you have more than 1 user with a talk group number that is the same. For example some fire departments and maybe a public works dept. will use the talk group number 1, and the radio will not accept that number a second time.

So far none have understood your question it appears. The critical point is that only the Contact ID number is what is important. Whatever you "name" it is only for your benefit. So yes, you can only program any TG#nnn once, but that doesn't really matter!

For example, while "WW Global" is TG#1 on DMR-Marc (and other ham networks), on the XYZ Company DMR system TG#1 might well be "Management".

So, you could set up a Zone for the XYZ Company, and still use TG#1, but on your screen it will still say "WW Global"...