Simplex repeater feature released

[RFguy]

Looks like there is a simplex repeater type functionality called "Direct Range Mode" for MOTOTRBO 2.0 radios as part of the 2.7 software release.

Not sure how it works, but sounds like a SLR5700 unit is required (maybe other models too) and will act as a simplex repeater.

I suspect it receives on TS1 and transmits on TS2. Looking forward to trying this out.

[PETNRDX]

Having read the standard for DMR, I wondered when someone would come out with that.
Should be a practical thing to do.

[Astro Spectra]

There was a how-to on the other site that worked but needed double vocoding (it used back to back portable radios with an external electronic T-R switch).

If implemented in the SLR them it would be safe to assume it would be done "properly" but since I don't think the SLR platform has a T-R switch it's a little hard to see how the antenna connection might work.

It would be very nice if this was implemented in a mobile but hard to see how that would suit Moto's game plan.

[motorola_otaku]

In the TETRA world this is accomplished with store-and-forward. The DMO repeater radio receives and stores data from one timeslot and spits it out on the opposite. Since TETRA (and DMR) simplex works in an on/off configuration with sufficiently fast T/R switching this allows a subscriber radio to perform the repeat function. Whether or not the DMR simplex repeat function will work this way remains to be seen, but I cannot fathom a mechanical T/R switch on a repeater switching fast enough to work that way.

[Astro Spectra]

Sure, the T-R used would have to be PIN diode based (and was on the handheld implementation). My main point was that the SLR has a TX port and a RX port, so how would one use it as a simplex repeater without external hardware? Two antenna working doesn't seem likely.

[Bill_G]

If you have a SLR5700, why would you opt for simplex repeat? That makes no sense, and offers no advantages.

[tuckerm]

If you have a SLR5700, why would you opt for simplex repeat? That makes no sense, and offers no advantages.

Someone who couldn't get coordination for two freqs?

[Bill_G]

If you have a SLR5700, why would you opt for simplex repeat? That makes no sense, and offers no advantages.

Someone who couldn't get coordination for two freqs?

I gots me all these bicycle tires. Think I'll go put 'em on my pickup truck. See how good that works. Let's go boggin!

[RFguy]

If you have a SLR5700, why would you opt for simplex repeat? That makes no sense, and offers no advantages.

We have a customer that has a remote base opertating on a simplex frequency at a good location. Base to mobile/porable radios has great coverage. We have tried 3 times to get them a repeater pair and turned down each time. Not enough units.

This may be the answer to their problem.

[RFguy]

Looks like there is a simplex repeater type functionality called "Direct Range Mode" for MOTOTRBO 2.0 radios as part of the 2.7 software release.

Not sure how it works, but sounds like a SLR5700 unit is required (maybe other models too) and will act as a simplex repeater.

I suspect it receives on TS1 and transmits on TS2. Looking forward to trying this out.

Oops, That should have read "Extended Range Direct Mode"

[RFguy]

From the current system planner:

Extended Range Direct Mode
The Extended Range Direct Mode feature utilizes a time division duplex repeater that receives a direct mode transmission and repeats it 90 ms later, as described in this section.
This mode's primary purpose is to extend direct mode range while utilizing a single frequency.
(Note, this does not extend the range of Dual Capacity Direct Mode.) A radio initiates a transmission as it does in direct mode and can receive transmissions directly from a radio or from the repeater. At the beginning of reception the radio selects the best signal. Therefore direct mode operation is still supported in the absence of the repeater without having to change channels.
When receiving directly from a radio the receiving radio will display the talkaround icon. When receiving from the repeater the receiving radio will not display the talkaround icon.
Extended Range Direct Mode is a single site conventional mode solution that supports the following features.
• Voice Calls (Group, Individual and All)
• IP Data (Unconfirmed Group, Unconfirmed Individual and Confirmed Individual)
• Control (Radio Check, Radio Inhibit and Uninhibit, Remote Monitor and Call Alert)
• Privacy (Basic, Enhanced and AES)
• Restricted Access to System (RAS)
• Voice Transmitter Interrupt
• NAI wireline interface for voice and control for 3rd Party Voice and Control Applications
• MNIS Wireline Data gateway for MSI and 3rd Party Data Applications
• Remote Repeater Programming
• RDAC
• Analog CWID and FCC Level 1 Monitoring
The solution does not support the following features:
• Repeater Broadcast Hangtime Signaling (same as direct mode)
• Data Revert Channel
• Digital Phone Patch
• Enhanced Channel Access (same as direct mode)
• Digital Voting
• Digital/Analog Mixed Mode
• RAS Migration Mode

Interactions Between Direct Mode and SFR Mode Radios
If both Direct Mode radios and Extended Range Direct Mode radios are programmed with the same frequency, color code and talkgroup, they are able to communicate with each other in direct mode. However in the presence of the Extended Range Direct Mode repeater, there will be an imbalance in range that is dependent upon the receiving radio. The repeater will re-transmit either the Direct Mode radio's transmission or the Extended Range Direct Mode radio's transmission. However only the Extended Range Direct Mode radio will be able to receive the repeater's transmission. Because a Direct Mode radio will not receive the repeater's transmission there is an imbalance in coverage. Therefore it is recommended that Direct Mode and Extended Range Direct Mode radios are not used to communicate with each other in the presence of the Extended Range Direct Mode repeater.

Repeater TX/RX Isolation
The Extended Range Direct Mode repeater requires 30 dB of isolation between TX and RX ports. This can be accomplished by using two different antennas, one for transmit and the other for receive. The following chart can be used for guidance to obtain the required isolation.

Dipole Antenna Separation
Horizontal 20 feet for VHF 10 feet for UHF
Vertical 7.5 feet for VHF 3 feet for UHF

A single antenna may be used in conjunction with an RF switch capable of handling the repeaters TX power. GPIO output pin T/R Switch is be used to drive the switch.

[RFguy]

I don't get how an antenna relay would work in this application. Wouldn't the relay would be chattering away switching between RX and TX?

[Astro Spectra]

Solid state PIN diode switches or 'relays' are not mechanical.

[Bill_G]

From the current system planner:

Extended Range Direct Mode
...

Thanks for this C&P. It explains the theory of how it would apply in the field - by leveraging the second time slot, applying a small amount of delay, and isolating it in the subscriber receiver. That stops the echo effect (that stops) common (the echo effect) with (common) analog (with) simplex (analog) repeaters (simplex repeaters). It can drive you nuts if you are within range of both the original and the repeated signal. They either beat each other to death so nothing could be understood, or if enough recording delay was applied, every conversation took a really long time in very short bursts.

This might actually work. Store and forward was okay for low speed data, but was clunky for voice.

PS - I can see why a duplexer could not be used to achieve the required isolation.

[Bill_G]

If you have a SLR5700, why would you opt for simplex repeat? That makes no sense, and offers no advantages.

We have a customer that has a remote base opertating on a simplex frequency at a good location. Base to mobile/porable radios has great coverage. We have tried 3 times to get them a repeater pair and turned down each time. Not enough units.

This may be the answer to their problem.

Add units to the license request.

[Astro Spectra]

It's a cool idea but the dual antenna working is a bit naf. I think a PIN switch is the answer. I'm certainly going to try it.

A bit disappointing in that it looks like it doesn't support IPSC.

I wonder if all third party radios would work ok into the setup?

[motorola_otaku]

Yep, that sounds identical to TETRA DMO. Shame they didn't implement it in the portables and mobiles... any DMO-capable TETRA radio can function as a "hotspot."

I also didn't know high-power PIN diode T/R switches were a thing. Is this a commercially-available off-the-shelf part?

[RFguy]

I also didn't know high-power PIN diode T/R switches were a thing. Is this a commercially-available off-the-shelf part?

Dito.

Does anyone have a sample of a VHF/UHF one that will handle 10 to 50 watts? My quick search only showed low power or GHz type units.

Are there any critical length/impedance issues with an external PIN diode type antenna switch?

[Astro Spectra]

Well most modern day Motorola radios already incorporate PIN switches. They're easy enough to build, for example:

http://www.dj9kw.de/dj9kw/projekte/afu/ ... Pwr_Sw.htm

But note the that design lack the isolation needed for this application (30dB) so either the repeater power would need to be reduced to say 10W or the design built with better shielding. The task here is to avoid damaging or overloading the SLR's receiver with it's own transmitter output.

For an integrated part this is typical:

http://www.skyworksinc.com/uploads/docu ... 16_13A.pdf

There are lot of options here.

Another option is a good circulator but this has to work into a very good antenna. With best case antenna RL of 20 dB, the SLR transmitter would need to run at no more than 6W to meet the equivalent RX input level implied by the 30 dB isolation requirement.

[n1gtl]

Is 2.7 out? I just checked MOL and do not see it.

[Astro Spectra]

For those that don't like home brew here is an off-the-shelf PIN option that does what's needed:

http://www.xmicrowave.com/product/xm-a3n2-0409d/

Just needs connectors.

At $80, 40 dB isolation and 0.2 dB IL <500 MHz, and 45 dBm power (50W) what's not to like? I'd drop the repeater to 25W to be safe on the max power as we don't want compression. Even so a low pass filter or band pass cavity should be used in case of harmonics. You'd probably want a BPF of some sort anyway if this is going at a shared site.

[d119]

Seems to me this whole thing is a bit of a mess... How do you license it? FB? FB2?

Some things are better left alone, I've a feeling in the long run, this is going to be one of those things.

[n1gtl]

This list was provided to me for using an antenna relay system:

SCRTPG,M4X0.7X35,STARPAN STL ZINC

30009310002 CABLE, ANT RELAY DC

3084921Y21 RF CABLE,PA(N) TO ANTENNA RELAY(N)

40009272001 COAXIAL RELAY, 14V

[Astro Spectra]

If that's an electro-mechanical relay I don't think it will be fast enough. Perhaps it's a PIN model?

Did Moto recommend that for this specific application?

[n1gtl]

I called /\/\ and put the question to their tech support. The guy was going to forward to engineering. That's what the reply e-mail read.

[RFguy]

I called /\/\ and put the question to their tech support. The guy was going to forward to engineering. That's what the reply e-mail read.

That is so sad.

[RFguy]

Look for a PIN diode option to be available from Motorola in the next month or so.

[Astro Spectra]

I purchased one EID and done a quick test. I've not implemented a proper switch.

It does work but I can't report anything about performance yet. You do need the latest portable firmware for the subscriber radios you want to use as no combination of older simplex settings worked

[com501]

Does this use the 2 slot mode on the repeater, one side receiving the mobile, the other slot transmitting out? Doesn't seem to be a very useful feature in any case, since the REPEAT mode would do the same thing. ???

[RFguy]

Does this use the 2 slot mode on the repeater, one side receiving the mobile, the other slot transmitting out? Doesn't seem to be a very useful feature in any case, since the REPEAT mode would do the same thing. ???

Yes, the repeater RX's slot 1 and re-transmits on slot 2 on the same frequency. The portable radios transmit slot 1 and RX's on slot 1, but if signal drops below a threshold, then will use slot 3 for RX.

The benefit is where repeater pairs are not available. For example we have a public works department that has a VHF simplex channel but has been unable to get a repeater pair. The existing base station can talk everywhere, but they have problems talking portable to portable.

This will fix that.

[Astro Spectra]

Does this use the 2 slot mode on the repeater, one side receiving the mobile, the other slot transmitting out? Doesn't seem to be a very useful feature in any case, since the REPEAT mode would do the same thing. ???

Correct but this mode saves co-ordination for a pair but more importantly may save $1k (in the case of VHF) for a duplexer or an additional combiner port. You'll still need a cavity or two for a band pass filter at a shared site. My interest is in portable repeaters for VHF, while the SLR5700 is a little big Moto has some new toys coming which may help with size. Either way a decent VHF duplexer for even a 4.6 MHz split is quite large and adds weight to a portable package.

Yes, the repeater RX's slot 1 and re-transmits on slot 2 on the same frequency. The portable radios transmit slot 1 and RX's on slot 1, but if signal drops below a threshold, then will use slot 3 for RX...

Actually if the repeater signal is lost the subscriber radios TX/RX on slot 1, which is neat because if a search group go out of range they will still be able to talk between themselves without changing channels. I'm still testing this out.

[RFguy]

Yes, the repeater RX's slot 1 and re-transmits on slot 2 on the same frequency. The portable radios transmit slot 1 and RX's on slot 1, but if signal drops below a threshold, then will use slot 2 for RX.

What I meant to say was:

Yes, the repeater RX's from portable/mobiles on slot 1 and re-transmits on slot 2 on the same frequency. The portable/mobile radios transmit slot 1 and RX's on slot 1, but if the RX signal from other portables/mobiles drops below a certain threshold, then the receiving radio will use the slot 2 signal from the repeater for RX.

[motorola_otaku]

Actually if the repeater signal is lost the subscriber radios TX/RX on slot 1, which is neat because if a search group go out of range they will still be able to talk between themselves without changing channels. I'm still testing this out.

Okay, that's pretty slick. I'm already envisioning how this could be useful for extending in-building coverage for events and temp/rental setups.

Too bad we'll never see innovation like this in the P25 world...

[xmo]

"...Too bad we'll never see innovation like this in the P25 world.."
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I think you'll see plenty of innovation. How about this. With an APX8000 (and obviously everything configured and programmed correctly) if you go into a building and go out of range of the system - if the radio finds a wifi signal, it will affiliate there and connect back to the system CORE through the Wave server and put you right back on your talkgroup.

[RFguy]

"...Too bad we'll never see innovation like this in the P25 world.."
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I think you'll see plenty of innovation. How about this. With an APX8000 (and obviously everything configured and programmed correctly) if you go into a building and go out of range of the system - if the radio finds a wifi signal, it will affiliate there and connect back to the system CORE through the Wave server and put you right back on your talkgroup.

Yes, and coming to your XPR e series radio later this year. Now a supervisor can take his radio home (or anywhere else in the world that has WiFi) and talk to his team back at the factory/mall/warehouse on the system talkgroup.

[Bill_G]

There goes the BDA business ....

[motorola_otaku]

"...Too bad we'll never see innovation like this in the P25 world.."
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I think you'll see plenty of innovation. How about this. With an APX8000 (and obviously everything configured and programmed correctly) if you go into a building and go out of range of the system - if the radio finds a wifi signal, it will affiliate there and connect back to the system CORE through the Wave server and put you right back on your talkgroup.

Sorry, I meant that more along the lines of "we'll never see APCO pushing innovation like this in the P25 standard" a la conventional Phase II and simplex repeat capability like this.

I've sat in on a couple of WAVE demos. It's a neat toy, but at the end of the day it's still a toy.