RD982i-S *Analog* IP Multisite Connect (but...)

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intermod

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I was looking for a less time-consuming method to link two *analog* GMRS repeaters without all the external hardware, level setting, COS/PTT, blah, blah...that operates in parallel with the DMR IP connection (we had already linked them though IP for DMR). I found that Hytera's "S" (super or system model) provides for analog linking over IP with no additional hardware (likely proprietary to Hytera). Their Planner document indicates that up to 15 other repeaters can be connected with this feature.

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Unlike Motorola they allow IP Multisite Connect to function while in mixed-mode (and mixed-mode comes built-in). And it has a rudimentary multi-tone/community tone panel capability (compared to Zetron), perfect for GMRS.

Analog transmissions on either repeater were sent to the other via the IP connection and retransmitted in analog. Audio quality was the same as local repeat. The transmitting user's CTCSS/CDCSS encoding was filtered/removed and not sent to the far end (just audio was sent). The CTCSS/CDCSS transmitted by the far end repeater was the code set on its mixed mode channel screen.

Use of any of the CTCSS/CDCSS uplink codes in the multi-tone list resulted in audio being sent over the link (seems you cannot limit linking to specific codes).

The built-in speaker monitors both the repeater receiver as well as the audio received over the IP link - this includes analog and one or the other slot of digital audio. It also has a local microphone connector and display. Nice...... Manual indicates repeater may be able to decode DMR audio on each slot and send analog audio to separate accessory pins for various purposes. I did not experiment with this.

I expected that the remote repeater would not key if IP traffic was limited to one slot. But disabling networking on Slot 2 (e.g., to allow for local DMR comms only) still keyed the far end repeater in DMR, although no voice was conveyed; Hytera indicates this is to busy the remote repeater to prevent over-transmission (presumably from a remote analog user),. They indicate this can be time-limited on the remote repeater by playing with SIT and a few other settings (not yet attempted). Alternatively, the repeater has a field to filter talkgroups for local or wide-area...but this seems inoperative.

But the most significant drawback on this model is that discriminator audio access is disabled on the accessory connector. For many users it won't matter, but I often run an external CTCSS/DCS decoder to monitor tone activity, or use it for other purposes. So, if you choose to use a more "open" analog linking method that needs unfiltered RX audio you will be SOL. Hytera claimed this was a hardware limitation - maybe they needed this audio path for the Analog IP linking.....but its unclear. The only thing available is speaker audio (via tap on the main board) which is heavily filtered with no flat option of course.

Another minor drawback is that its transmitted audio contains noticeable hiss - I suspect it does not meet their 40 dB hum and noise spec, but Hytera often has marginal audio designs, usually RX audio though. Also, while Hytera's squelch design can sometimes lack hysterisis and contain some gating transient pops (DC in the analog switch - DUH), its squelch handles weak fading signals better than the SLR5700 when the squelch is optimized.

We continue to test this model as a more flexible replacement to Motorola's increasingly dysfunctional products - but it remains to be seen if making Homeland Security's shit-list (likely with the help of Moto's lobbyists) impacts availability.
 

RFI-EMI-GUY

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I think this thread should be a sticky. I think the technology has a lot of practicality for not only commercial where it was intended as a transition for DMR but for GMRS and Ham.
 

PSEhub

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What we really need is cheap simulcast in 1 RU form factor

Enough of this over engineered BS

Hytera requires 6+ rack spaces and a centralized "switching" office, and its pricy

The Mototrbo digital voting kicks ass, and doesn't require extra hardware. but without simulcast its less useful

To Motorola's credit, they also don't charge for most EIDs on satellite receivers.

I've set up "cellular" DMR with SLR1000s and Yagis as sattelite receivers, and a SLR5700 with power amplifier.

This has the benefit of no duplexer insertion loss, and no feedline loss on receive.

But true, CHEAP simulcast would be nice
 
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intermod

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Completely agree on simulcast. The roaming function is marginally useful. The various SLR repeater models have a GPS antenna input - presumably this was for simulcast and not limited to just frequency stability. It does not need to be difficult. The challenge with DMR simulcast is limited site separation as no linear simulcast exists for it yet. But it would be fine for a small city and especially for a large campus. Larger cities could actually use a combination of roaming and smaller simulcast cells, but the goal is always to eliminate roaming when possible - that is where all the issues occur.

The Mototrbo digital voting has at least one annoying limitation. If I recall, each receiver could only be associated with a particular transmitter (and the repeater's receiver must be associated with it integral transmitter). If you had two (or more) overlapping transmitter sites, each transmitter would only have a subset of the total number receivers, and each set must use a different RX frequency. So you could not benefit from having all receivers on the same RX freq listening for all mobile transmissions. This is because a mobile transmission may be heard by both comparators and the voted audio packets would collide.

Maybe having one common RX freq does work put the planner said differently.
 
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