Deploying a Mobile Repeater


This is a help guide on how to bring a repeater onto an IPSC network,  primarily for use in a motor vehicle while traveling outside of the traditional coverage areas of fixed repeaters.

Mobile repeater Manager  --  More Considerations   --  Repeater in a Box


There are a number of considerations to address in a networked mobile repeater as well as what the repeater owner wishes to accomplish after deploying the repeater.  No matter how simple or complex the needs, all installations will need a minimum of the following:

  • TRBO repeater (1-25 watt low power likely preferred)

  • Wireless data service

  • 12VDC in the vehicle

From this simple list, one can add additional components to accomplish much more:

  • 0, 1 or 2 antennas (no antennas are actually "needed")

  • Duplexer (flat pack preferred, simple and cheap)

  • Battery back-up (other than primary start battery for vehicle)

  • Flexible 12 VDC power-pole distribution/ management with battery re-charging

  • Laptop use requiring DC power and Internet service

What you choose to use will likely be driven by what your "needs" are in a networked mobile repeater environment.  If all you need is to have a networked repeater while you are driving or stopped for a restaurant or other short periods out of the car with needs to provide HT access, then the short list above can work adequately.

At the other end of the scale are deployments that must run 7/24, higher RF levels for larger coverage areas, Internet access to multiple devices or to to service public service events, civil emergencies, search and rescue, ham conventions where you must get into the arena, shopping mall excursions or trailhead hiking.  Disclaimer:  We don't know it all, so don't trust us with your time and money and if you know more, how to do it better, please let us know so that we can incorporate it here so that it can benefit those who may come after us.

Once you settle on "need" and have the components, it would be helpful for you to know how best to get it on-the-air quickly and more effectively...so that it can work on the first trip out.  That is the real purpose of this page.  Using what we have done by trial and error on the Verizon data network and understanding  what can and cannot be controlled should help you make it a working project that can be counted on to perform dependably for a wireless connection in motion.  Much of this information can be applied to any service provider as well as the hardware needed to get data into a TRBO repeater.

Obviously the wild card in this project is the wireless data service.  We assume you already know how to deploy a garage repeater onto an IPSC network and only the Internet in motion is the key variable.  It is the linchpin of course so this page will focus on the data side primarily.  TRBO only uses an average of 18 MB per day for an average 5 repeater network connected to DCI and MARC feeds with typical  TX times into the mobile repeater.  Even on the $15 for 7 day pre-paid tier, you will should never use your miserly 250 MB allotment.

We began with a cradlepoint router and Verizon USB LTE dongle for Hamvention 2012.  We are now supporting the MiFi solution actively...because:

  1. It works; some models support external cellular antennas, a very helpful option

  2. It is very portable; double duty for hotspots in your pocket, stationary and TRBO

  3. It is useful for both repeater and other data; laptops, tablets and smartphones

  4. Relatively inexpensive (~$100-$200 new, pre-paid, pay as you go and $20 monthly as a 2nd device)

DCI has 2 repeater owners who have MiFi and have used them for TRBO repeaters on the road in the last few months for several thousand miles of experience.  Other solutions are out there certainly.  Our bigger problems have been data, UDP and changing public IP's on the mobile repeaters, but much of this information should still be useful to those who care to use other services and cellular data devices.

So having set the stage for this project, let's move on to cellular data and getting it into your repeater.

Verizon MiFi 5510L (no external antenna port) and MiFi MHS2911 (with external antenna port)

The MiFi has the best USA coverage and is inexpensive to use for TRBO.   Some models may be more useful as they may have a cellular antenna port which will enhance coverage over the internal antennas especially if you will be traveling through rural areas of the country.  Other benefits with a MiFi are that they are handy, portable, battery powered, very small and can be used for other data purposes to soften the overall cost of ownership if only used for a mobile TRBO repeater. 

Service can be as cheap as $15 (250 MB @ $2.15 a day for 7 days) or $60 (60 GB @ $2 a day for 30 days) for pre-paid or as little as $20 a month for an additional MiFi device on an existing/shared data plan.  See: Verizon Data Plans

MiFi's support ONLY WiFi connections, so one needs to use a bridging device to change the WiFi to Ethernet.  We use the Ubiquiti Nanostation Loco M2's as they are high quality, low cost devices, only $53 from Amazon and we had them in stock for use normal data point to point solutions for other TRBO projects.  Any other client bridge can be used also.  Once the M2 is configured, it needs no further attention as it will auto connect to the MiFi device upon power up.  See:  Loco M2 set-up

Be sure you repeater is programmed correctly for M2 client bridge.  You may use DHCP or Static on your repeater.  We suggest DHCP (and these pages support it) so that the repeater can move  from the stationary location to the car and not need to necessarily open CPS to make any changes.  Static IP for the repeater is fine also.  Be sure your client bridge is set up to match the repeater.

Once on the network, does it work?  We use the c-Bridge Net Watch page for it's extensive diagnostics.  One can use RDAC also but that requires a PC and most tablets can use Net watch via the web browser to check repeater operation on the network and UDP ports.  However you manage it, it is handy to be able to monitor your network while deployed.

Other items for Mobile Repeater Installs

  • IPSC Network Master; physical, c-bridge or SmartPTT and why or why not (important)

  • Antennas, Duplexer and Frequency separation

  • current draw of all devices

  • typical data use; very little for TRBO (18mb a day for 5 repeater network; 1+4 with MARC/DCI)

  • Number of peer devices on the IPSC network is a consideration and why

  • Determining if you are on or off the TRBO network (on or off Verizon's network to a lesser degree)

  • LTE, 3G, 2G and which is best to use and why

IPSC Network Master:  This is important.  You should (must) be on an IPSC network that is running a physical master repeater such as the common 8300's or 8400's.  If your network is using a c-Bridge or SmartPTT as a master, then your results are very likely to be disappointing.  It appears that the 3rd party solutions are not as robust or compatible to a mobile deployment.  We feel this is due to both varying IP's and UDP ports that are constantly changing as the repeater hand-off to different cell sites.  The physical MotoTRBO repeaters appears to handle these variations far better and this keeps your repeater on the network much more consistently than a 3rd party device.  If you repeater is not in motion, then we have found that there is little to no consideration to the type of device used (data service).

Antennas, Duplexer and Frequency separation:  Consider your use of zero, one or two antennas.  If you plan to use your repeater only while driving, no duplexer or antennas are needed and you can use your mobile radio or HT.  If you want slightly better coverage while outside of your car, put a spike on the receiver.  If you want fair coverage but no duplexer, use a mag mount spike on the TX and stick it to the repeater chassis and put the receiver on the roof mount.  If you are not using a duplexer at all, consider using a 15 meg split for better coverage as well as the lowest TX power setting possible.  We use 1 watt out into the spike and a rooftop gainer on the receiver and with a 2 watt HT, have better than .5 mile coverage through a pine forest with -95 dBm RSSI on the HT and -59 dBm RSSI on the repeater when deployed on a 15 meg split.  If you need high power and wide area coverage then you must use a duplexer and the 6 cavity flat packs are perfect for this purpose.

Power up with 12VDC:  All devices work fine on 12 volts.  Current draw is about 2 amps for the repeater idling and 2.5 while TX'ing at 1 watt.  Add .5 amps for the MiFi and M2 client Bridge and you are well under 4 amps worst case.  Battery backup is worth considering if you have any plans to let the the repeater run for long periods of activity or overnight.  All power can be tied to one point for ignition on operation or use an always on point.  The better approach is to run on back-up battery (ASM's or gell cells) and add in re-charge when engine is running.  You will need to get 12V into the battery revert port on the repeater, AC optional if you plan to be stationary for long periods but the revert will only re-charge at 500-600 mA.  You might add a small Astron PS to the 110 option to quickly bring the batteries back to full charge.

Typical data use:  It may surprise you how little data is needed for TRBO communications.  We have found that with a 5 repeater IPSC network connected into both DCI and DMR-MARC uses about 18 MB a day with typical activity day in and day out.  If you must keep to a minimum amount of daily data consumption you can either limit your TX time into your mobile repeater or have fewer peers on the IPSC network you are using.  The more peers and active timeslots on the network (only while you are transmitting into your mobile repeater) the more data required.  Even on the stingy 250 MB Verizon pre-paid plan, this should never be an issue.  You actually can go mobile repeater for a week to Dayton and back for $15.

Determining if you are on or off the TRBO network:  Unless you hear networked activity from your repeater in motion, you will not know with any certainty, that you are actually, connected to the IPSC network.  The c-Bridge Net watch easily provides you that clue.  Many c-Bridge owners have graciously enabled guest accounts for use by the TRBO community.  There are also last heard lists made public, and now this live last heard from DARC.  But the best way to determine complete and working connectivity is to have a conversation.  Well that is not going to work for monitoring so an active c-Bridge Net watch is really what you need.  Those require higher level accounts with much proprietary information, so that is not likely to be available, but this DCI Last Heard can help, though use must manually refresh your browser.  So what is the solution?  If EchoLink of TRBOVUi is available, wonderful.  Again not likely.  So, for now until there is really nothing readily available.  Maybe a Parrot talkgroup will some day grace our networks.  Or worse, a touch tone enabled talk-back device much like the EchoLink test server.

LTE, 3G, 2G: Which is best to use and why?  This is a bit sketchy at this point and input would be appreciated.  When we used a Cradlepoint with a Verizon USB dongle for 5000 miles to Hamvention 2012 and back, we found that we had fewer issues with tower hand-offs if we ran at 2G connections.  Our recent experiences with MiFi tend to tell us LTE is OK to use.  At this point, if you are not needing  LTE speeds for a laptop or tablet, it may be best if you lock down to EVDO only.  More on this if/when we gather more input.

Other odds and ends, tips or hints...tis the catch-all bin

  • Place your MiFi so you can watch it's display; know that you have service, it's strength and data consumption if you are on a very limited plan, especially if you are using a tablet or PC to monitor the network and/or Email etc.

  • Buffering delays; if you can hear audio from land based TRBO network, the delay experienced through Verizon is a function of signal strength; 2 seconds is good, 5-20 seconds is very poor.

  • Signal Strength; RSSI's less than about -95 dBm are subject to delays, audio drop-outs, poor comm quality.

  • EVDO suggested; 1x is not useable, LTE is not yet in wide release, locking to "EVDO only" is likely to be the best overall setting to limit the number of service changes as you move between 3G, 4G and LTE areas.  If you are in a major urban area, leave the MiFi set to automatic.

  • Signal drops and tower hand-offs; typically 30-45 seconds is needed before your repeater comes back on the IPSC network if Verizon service is dropped or has a poor tower hand-off.

  • Permanent vehicular WiFi; MiFi may not be the best device for long term use in a vehicle and the Cradlepoint may be the better solution.  Unknown if the the current Cradlepoint/Verizon combination works as well as the MiFi for this specific TRBO use.  Traveling to Hamvention 2012 we found they did not.  More input is needed.

  • Repeater Fan Control; I have a DPDT center off mini-toggle mounted above the PS fan; down is PS fan only, up is PS and TX fans enabled for normal operation.  The PS fan runs when powered by 12VDC and is noisy inside the vehile as well as when the ambient air temp is high, the TX fan ramps up like a jet even though the TX is ambient cool.  Now, while running 1-5 watts on 12VDC, I have the choice between fans...and still normal duty when returned to stationary use on 110VAC and at higher TX power.


We would appreciate feedback on your mobile repeater experiences and especially your experience with MiFi and Cradlepoint while in motion.  Please Email: dci@trbo.org

Revised: 09/22/2014 15:58

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