OpenGD77 - Repeater

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G0FHM
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OpenGD77 - Repeater

Post by G0FHM » Fri Oct 11, 2019 1:48 pm

Hi,

I'm running a Radioddity GD-77 with Opengd77 firmware as a Hotspot.

I have a second GD-77 on the way. Would it be possible to run 2x 77 with Pi-Star to make a low power quick and easy repeater?

I've no idea how much work it would entail, as I'm in no way a software engineer!

Food for thought?

73

James G0FHM

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Re: OpenGD77 - Repeater

Post by AF6VN » Fri Oct 11, 2019 3:33 pm

Pi-Star is just the OS/application running on a Raspberry-Pi.

The capabilities you ask for depends upon the radio board mounted on the R-Pi.

I believe you are looking for a duplex board with PTT/Audio-Out (for the repeater transmit radio) and Audio-in (for the receive radio) [vs a duplex hotspot board that has internal low-power radios]

https://n5amd.com/digital-radio-how-tos ... -repeater/ indicates that it uses ANALOG (FM) radios (to transfer the "buzz" of digital data -- the mmdvm board converts the "noise" back into true binary to pass to the R-Pi for network processing.

Note: duplex is not the same a dual-band. Dual-band boards have on-board radios that can operate on either 2m or 70cm, but are simplex hotspots on either band. Duplex boards operate in the same band (though separated by normal repeater splits) and can output on one while receiving on the other.

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KE0FHS
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Re: OpenGD77 - Repeater

Post by KE0FHS » Fri Oct 11, 2019 4:00 pm

James, I have no idea if what you're talking about is possible. The project you're referring to essentially turns a GD77 into a higher power simplex hat by installing the special OpenGD77 firmware being developed by Roger Clark, VK3KYY (https://www.rogerclark.net/) onto the GD77 and plugging it into a Raspberry Pi running Pi-Star via USB cable. I haven't tried it yet, but have been following the posts of some hams who have. It sounds pretty cool, and I intend to try it myself in the not so distant future.

But would it be possible to link two GD77s together? Have you tried asking Roger directly? It is possible to leave a reply on his posts and he also has an email address listed on QRZ.
73, Toshen, KE0FHS
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VK7HSE
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Re: OpenGD77 - Repeater

Post by VK7HSE » Fri Oct 11, 2019 4:13 pm

Short answer is no!

Longer answer is that what you suggest might not be even possible from the software.

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G0FHM
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Re: OpenGD77 - Repeater

Post by G0FHM » Sat Oct 12, 2019 9:41 am

As I said, I'm no expert.

Pi Star supports duplex hats (although i'm not sure whether they are "repeaters" per se, i've never used one). The GD77 is basically operating as the modem in the place of say a zumspot hat or similar, albeit via USB as opposed to the GPIO pins on the Raspberry Pi. I have one GD77 operating with Pi-Star on a Pi 3B+ and it's working well.

Surely it shouldn't be that hard to add a second GD-77, with one operating on the "input" and the other operating on the "output", with the resulting voice/data being passed from one GD77 to the other. Basically like a duplex hat, but using 2x GD77. I'd say that would be a Pi-Star development thing rather than OpenGD77.

The OpenGD77 firmware development state only supports "Tier 1", but from what I have read the "Tier 2" update is not that far away. I'm not sure if that would have a bearing on what Im proposing or not. Basically the GD77 in hotspot mode is just providing the "buzzing noise"

As I said at the start, I'm no expert.....

73,

James G0FHM

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Re: OpenGD77 - Repeater

Post by M1DNS » Sat Oct 12, 2019 10:53 am

As with any new hardware pi-star can write in support for it if the demand is there. Obvs. it's much easier if we have access to that hardware, either owning it ourselves or accessing it remotely etc. But the support will only come if the demand is there, and the feature benefits a great percentage of users. There's already plenty to keep up with, and only X hrs in a day.

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VK7HSE
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Re: OpenGD77 - Repeater

Post by VK7HSE » Sat Oct 12, 2019 11:07 am

The OpenGD77 as a hotspot will only be a tier1 device. It's hardware can't support transmission and reception simultaneously.

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Re: OpenGD77 - Repeater

Post by M1DNS » Sat Oct 12, 2019 11:19 am

VK7HSE wrote:The OpenGD77 as a hotspot will only be a tier1 device. It's hardware can't support transmission and reception simultaneously.

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ImageImageImage
Obvs. support will only be considered for something that is proven to work.
Beta hardware projects won't see support until it's known/proven/shown that it does what is intended. :-)


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G0FHM
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Re: OpenGD77 - Repeater

Post by G0FHM » Sat Oct 12, 2019 11:30 am

Hi Andrew,

Thanks for a sensible response!

I have a second GD-77 on it's way. I think it could be a popular addition, as you would have a 5w quite easily portable repeater, ideal for RAYNET or other such EMCOMM groups. The downside could potentially be that anybody could start popping up with unlicensed repeaters.....

When I get the second GD-77, I can always plug it in to the Pi, and if a member of the dev team wants too SSH in and have a snoop around (if it will help), then by all means, feel free.

I have an application for GB7GS (70cm DMR) in the vetting system at the moment, and it would be nice if it could be the first OpenGD77 repeater, rather than doing it the "traditional" way.

Cheers,

James

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Re: OpenGD77 - Repeater

Post by M1DNS » Sat Oct 12, 2019 11:56 am

Personally I'm in favour of using a repeater board with a mobile radio(s)
5watts from a 25w radio will give a much better / cleaner signal. When it comes to wide area coverage or servicing a given area etc.

As an adjunct several yrs ago I used a Kenwood handheld with a dstar card for just such an entry point into the dstar network, but it got very hot in TX on the busier reflectors where the conversation was continuously being passed between several hams, due to the near constant tx and limitations to cooling etc. with a handie.

I wasn't aware of the gd77 firmware thats been mentioned above, but I guess someone will find use for it, If it does indeed work.

Andrew M1DNS, (Mod)



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