This is a guide and installation document for a permanent
mobile repeater installation with tips on the gotchas
involved and how to minimize falling off the IPSC network
for the least frustrating experience.
Mobile
repeater Manager
-- Repeater in a Box
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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 with fan mod)
-
Cellular data service
(hotspot, phone tether, router)
-
12VDC in the vehicle
(cigarette lighter, direct to battery)
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 while in motion
-
110 AC provisioning
for long deployment cycles and quick recharging of the
batteries
-
Laptop/tablet/phone use
while in vehicle, stationary or in motion (for
passengers not the driver)
What you choose to use
will likely be driven by what your "needs" are as
well as their associated
costs to deploy a
networked mobile repeater. 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 service public service events,
EMCOMM, 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.
From this point on, all
information provided will be from this installation
perspective based on what we want from this repeater.
Some notes will be added to help in other common areas as
well in order to help others who have somewhat different
goals. We have done this 3 times for over 7,000 miles
and have consulted with another hardy soul who has deployed
multiple times for several thousand miles.
OUR GOALS:
-
Semi-permanent, full time repeater, low power RF
output
-
Best RF
cellular coverage, moving mobile network
connected repeater
-
Reasonable
stationary HT coverage and duration.
CONSIDERATIONS:
-
Easy movement
to and use in another vehicle
-
Low
consumption of data and 12 volt power
-
Use of data
connection for other devices; computer, tablet,
phone via Ethernet and/or WiFi
-
c-Bridge
manager, ideally programmed for only 1 mobile
repeater resident at any 1 time
-
Least amount
of irritation to passengers from repeater
noise in the cab of the vehicle
OUR BASIC
EQUIPMENT:
-
Low power
1-25 watt UHF XPR-8300 with Fan Mods (more on
the mods later), flat-pack duplexer, UHF NMO
spike on roof
-
Cradlepoint
MBR95; 4G/3G/Cable/DSL, 4 port WiFi router with
support USB Cellular Modem with failover support
-
Verizon USB
Modem (Pantech UML295) dongle style, diversity
antennas with 2 external antenna ports, 2 4G/3G NMO gainers on roof
-
12 volt
power, harnesses/cabling for repeater, router,
and battery, with handy switches
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So having set the stage
for this project, let's move on to the nuts-n-bolts needed
and the details to make it all happen.
IPSC Network Master:
This is important. You
should (must or ideally) deploy your repeater on an IPSC network that is running a
physical master repeater with few to no other peer repeaters.
This is likely not going to happen with most IPSC networks.
So...next best and much more likely...
If your network is using a c-Bridge or
SmartPTT as a master, then your results may be less
robust. It appears that the 3rd party
solutions are not as compatible to a mobile
deployment as is a real TRBO Master repeater. We feel this is due to both varying IP's
and UDP ports that are constantly changing as data
connection
hands-off to different cell site groups or regions. The physical
MotoTRBO repeaters appears to handle these dynamic conditions
in peer repeaters far
better and faster which 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).
We also have learned that the c-Bridge is now handling the
changing IP's of a peer repeater in motion better now, as
quickly as 15 seconds seconds most of the time.
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 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 antenna 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 have used 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 thick 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 higher power and/or
wider area of coverage, then you should use a duplexer and the 6
cavity flat packs are perfect for this purpose.
LTE, 3G, 2G, Antennas: 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 or CDMA or 3G only. If you are
transmitting while your connection shifts between 3G/4G,
then it creates typically a harsh burst of noice. And
this can happen fairly frequently, so stick with 3G if
possible. Tower hand-offs generally don't cause an IP
change but it is a set of towers in a larger group or area
that do, so you do not need to watch for towers on the
freeway.
We are using external
antennas (diversity) and suggest that they be considered for
the very best, lowest frustration deployment. If you
deploy roof-top diversity antennas, then place them at least
20 inches apart for best results at 700 Mhz LTE.
Remember you do not need maximum data connection but the most robust
connections. Even in strong signal areas, multipath
and other interference can cause issues that a diversity
antenna system will minimize.
Power up with 12VDC:
Both the XPR-8300 low-power repeater and the Cradlepoint
MBR95 router work fine on vehicular 12 volts (your mileage
may vary if you are a DC purist). Current draw (engine
off) is 1.1 amps for the router, USB modem and the repeater,
connected and idling. TX'ing at
1 watt adds another 1.3 amps for a total of 2.4 amps. Battery
backup is worth considering if you have any plans to let the
the repeater run for long periods of activity or overnight
and wish to insure that your start battery will not leave
you stranded.
Purists again may wish to keep all the transients out of the
repeater and router as well, so some isolation from the
starter motor (during start conditions) is of certain value.
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, gell cells or possibly SLA's) and add in
re-charge when engine is running (simple relay energized by
"ignition on" to bridge battery to vehicle 12V system after
the motor start cycle as has ended) and a few handy switches
to control auto-manual charging and power to the repeater).
Another simple method is
to use a solar power controller to isolateyour run battery
from the start battery and protect from over-charge as well
as deep discharges. A super inexpensive
20 amp controller is on Amazon for about $11
delivered and there are many similar clones to this
particular controller. My 22AH SLA runs for 12-14
hours typically depending on the transmit time. I just
parallel up another for double the capacity. No
switches needed and use of Anderson Power Poles throughout
make changing the lash-up very simple and that is handy for
vehicle changes.
Secondary 110VAC:
Longer stationary times may be enabled by way of a handy
110VAC source. Adding in a small switcher power supply
to rapidly recharge your run battery as well as power to
your repeater, is worth considering. The combo
power/battery revert jack on the repeater will only
re-charge batteries at 500-600 mA which may be to slow to
adequately recharge your dedicated run battery, so do not
rely on that feature. The 10 amp switcher I use
presents a high impedance when not powered up, so it sits on
the battery 7/24. A motor home would be very
simple for an installation as both 110 VAC and 12 VDC run
battery connections are handy throughout most rigs.
I'd suggest having both sources if convienent.
HT or Mobile Radio
Use: An HT should be available even if you have a
mobile radio in your vehicle. You likely will want to
be able to use the repeater while outside the vehicle.
A mobile radio is handier to use while driving but it is
also more problematic with repeater riding along.
Mobiles are typically it is set up for high power and you
don't want 40 watts just a few feet from your repeater
antenna. Consider a dummy load and or reducing your RF
output, both a pain if that same mobile radio is to be used
with stationary repeaters or other standard uses; analog,
simplex, scan LE, etc.
HT's work fine with a
repeater on zero, one or two antennas and for a temporary
install in the YL car's trunk, no antennas or duplexer, are
very simple. Adding in the antenna, duplexer makes for
a more complications and time but provides more and/or
better coverage away from the vehicle. So consider the
trade-off's vs. benefits when making your overall deployment
decisions.
Determining if you
are on or off the IPSC 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. Use the Parrot
talkgroup to quickly and simply determine if your repeater
is working on your 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. Other possible
solutions may be EchoLink or TRBOVUi, though not likely nor
simple for a driver in motion to manager.
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
is consumed. Even on
the stingy 250 MB Verizon pre-paid plan, this should never
be an issue.
Repeater in a box:
This is NO7RF's version of a permanently deployed (if not
mounted) repeater. The design was to enable reasonably
easy moves between 2 primary vehicles as well as use in most
any vehicle if needed. The UHF duplexer/antenna is
optional as I typically use a "leaky" resistor dummyload on
the transmitter connector and spike on the receiver
connector, good for about 1/4 mile through heavy trees and
not line of site. See the "repeater
on a box" page for more details and pictures.
Other odds and ends, tips
or hints...tis the catch-all bin
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Use the handy
Parrot talkgroup to confirm IPSC connectivity; great
to have while driving
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Place your MiFi/USB
Modem/Router so
you can watch it's connection status; know that you have
service, it's strength and have a better idea of
your IPSC status while in motion. This can help
reduce frustrations when you can't take the time to look
at netwatch.
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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.
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EVDO or CDMA suggested;
1x is not useable, LTE is gaining in availability,
locking to "EVDO or CDMA or 3G 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, use the automatic setting, especially
if you are sharing your connection with laptops, tablet,
smart phones, etc.
-
Signal changes/drops and
tower region hand-offs; typically 15-20 seconds is needed
before your repeater comes back on the IPSC network if
Verizon service is dropped or has a poor tower or region hand-off.
Physical Master repeater networks are generally faster
and more robust for automatic IPSC re-connections than a
c-Bridge acting as the master repeater but the c-Bridge
as mater is much more robust with the release of
RVN8200.
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Temporary WiFi
Hotspots: While smartphones, MiFi, FreedomPop
and others do work, they are a poor choice for other
than occasional use. The soft switches, internal
batteries or tethering of phones is far more
problematic. You would also need a client bridge
to get that WiFi into an Ethernet cable for the
repeater.
-
Permanent
vehicular WiFi; The Cradlepoint MBR95 does not have
external antenna jacks so it is not entirely appropriate
for distance away from the vehicle (hotel, shopping,
etc). Consider a router that supports external
antennas if you want longer hotspot range.
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Repeater Fan
Control; Mount a DPDT center off mini-toggle
on the chassis 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
vehicle 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, there
is now a choice between no fan noise and save up to 1.5
amp/hours as well. The repeater can still operate normal duty
when returned to a stationary use.
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