Another issue is the FT-8900 doesn't
have the T/R switching speed to enable it to be a fully Tier II
compliant radio. I agree with Steve, the best solution for this
scenario is an analog repeater/gateway, with DVSwitch behind it
for access to the digital networks.
On 2/11/20 7:25 am, Steve N4IRS wrote:
Yes, you can mix and match components from a number of different
project. The radio you describe would have to pick off the analog
audio from the mic, send it through a vocoder and then send the
datastream back to the transmitter and on to the DMR repeater. In
the receive direction, the radio would have to pick off the the
audio from the discriminator, send it to the vocoder. The analog
audio would need to be injected back into the radio so the audio
could be sent to the speaker. As of this is doable. There is one
actual problem. The MMDVM software can look like a DMR repeater
transmitter to a subscriber radio. The MMDVM software can look
like a simplex signal (DMO) to a subscriber radio. What the MMDVM
software can not do, is look like a subscriber radio to a DMR
repeater. The same is true for traffic from a DMR repeater to the
radio. The MMDVM software can not receive the output of a DMR
If I were trying to accomplish what you seem to want, I would put
my money into the hill top repeater. I would build a high quality
analog repeater. The would give you the best mobile coverage. Now
couple that repeater with a Digital Voice bridge and you not only
get DMR, you get all 5 digital modes plus analog repeater
networking. This does assume the hill top repeater has internet
access as would a DMR repeater.
Just my take. YMMV
73, Steve N4IRS
On 11/1/20 3:01 PM, Jim Kusznir
So, as I reread this and talked to others, it sounded like my
request may not have been all that clear, so here's another go,
more from application than technical function:
I usually am mobile while on ham radio (VHF/UHF). I just
recently installed an FT-8900. In my area, due to terrain, 6m
is used (and is occasionally the only reliable way to get out).
Cell tower coverage is pretty spotty.
I'm looking to use an existing wide-area DMR repeater
transmitting on actual ham bands at "repeater power" located on
hilltops with wide range. I'm looking to do this mobile, where
an HT would NOT cut it. I would rather not have two completely
separate radios and antennas in my vehicle, and the only viable
mobile I've even considered to this point is the Anytone 578.
Unfortunately, even if I did go the dual-radio route, the
Anytone does not allow for separating the control head, and that
is required in my vehicle. So, that leaves me with no ability
to use DMR when mobile, which is 90% of my ham radio activity.
What I wanted was a way to do DMR with my existing FT-8900, much
like I can do 9600 baud packet with my FT-8900 by plugging in
additional equipment to the jack on the back of the radio. I
was hoping to create a "DMR TNC" with its own little display,
mic, and speaker, and have it connect to my FT-8900 and use it
as a CLIENT on the DMR system, and NOT need any internet in my
vehicle (or immediate vicinity).
So, to accomplish this, I see:
1) there ARE software packages that can work with a Pi to
connect via IP to the DMR network and run as a client (with a
mic/speaker), allowing all talk group access,etc., available on
the IP connection you are using. This is 1/2 of what I was
looking for, but no IP connectivity to the DMR network...I want
to use my radio.
2) there are solutions for using a Pi to connect to an analog
radio and turn it into a hotspot/repeater and connect to the DMR
system with IP. However, I am not looking to be a "repeater"
(server) but a user (client).
Ideally, I would like to take parts from both of the above and
"mash them together" so that my software frontend will interface
with a board (perhaps like the STMDVM, perhaps just an ADC like
NWDR's DRAWs hat) which will connect with the analog radio.
Yea, I will likely need something like the ThumbDV or some other
AMBE vocoder chip connected via USB....OK. The missing piece
seems to be some sort of software bits to act as an RF client.
I'm also wondering if this hasn't already been done because the
analog radio cannot switch its transmitter on/off fast enough to
do TDM as a client....If it actually isn't possible for this (or
other technical reasons), please let me know!
One more thing: I am NOT limiting options to "ready built
systems". I am a tinkerer, and I am good with linux. I'm sure
I could get a DMR-AllStarLink system going or other such stuff.
I'm not an outright coder, so modding the source code of the
client to implement what I'm looking for is beyond me, but I
don't require something as neatly packaged as PiStar (but would
gladly accept it if it were there!).
Thanks again all!
73 de Tony VK3JED/VK3IRL