GPS + GLONASS puck/mouse

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Bi111ion

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I have a Globsat BR355 GPS puck. I am pleased with it and it currently sends the VHF with position needed for DSC, powered of the same circuit (through a DC-DC converter) so when the radio is on it always has a position. We played a game on board in which the crew had to guess how many GPS receivers we had on board. It was quite a lot, including ones in the crew's phones, a camera, hand-helds (for back up!), even one in the hand held VHF. But the only one with Glonass was my Samsung Galaxy 4 phone.

So all that redundancy but except for my phone dependent on the good will and functioning US satellites. When we were sailing through Scotland in April the Coastguard warned that they would be testing jamming of the GPS signal. So that got me thinking that perhaps a GLONASS capable receiver integrated with the nav computer might be a good idea. In any case it would also be more accurate (the Samsung usually gives the most accurate position as it can see more sats, plus GlONASS uses two frequency bands).

So the BR355, a neat little waterproof puck with an RS232 output (comes with USB out as well) , uses the Sirf Star III chip set and cost me about 15 GB Pounds. So I was wondering if more recent ones using a later chip (eg Sirf IV) can get Glonass.

Here is a page in Russian that confirms such a thing exists http://www.globalsat.ru/catalog/gps-priemniki/bu-353-Glonass and you can but it for 3970 Rubles which is 50 GBP . I have found it on the Globsat website but teh spec does not say it can get Glonass.

So I was wondering, does anyone know if all Sirf IV based receivers can get Glonass anyway? Any other cheap Glonass capable pucks folks have found for good price?
 
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I think jamming GPS will very probably jam Glonass too.
They are in the same bandwidth, so many jamming techniques will affect both.
There are electronic warfare methods that will be selective OTOH.

There are ublox modules which do both, so you could either make your own or find a USB puck based on one.
 
On closer inspection the u-blox receiver is GPS or GLONASS not both, and has to be switched over by changing the settings. I would rather have both all the time like my Samsung.

It looks like SirfStar 5 chips do them simultaneously http://www.gns-gmbh.com/index.php?id=265&L=1 but I cant find a SirfStar 5 "module" is soldered on to a PCB at least with integrated patch antenna, just what appears to be the surface mount chip.

The SirfStar IV and V claim to have "Active interference canceller for GPS-in-band jammer rejection ". I assume this is not going to help with full scale military jamming, but would help with inadvertent jamming or perhaps deliberate jamming in an asymmetric conflict.

Maybe it is just a matter of waiting until they become available.

.. in the end I do still carry a sextant and I am not afraid to use it.
 
AFAIK, the major reason for wanting Glonass in a product is that the Russians get all stampy-feet about type approving anything that only has GPS.
 
Just to confirm MOD GPS jamming exercises do jam the frequencies used by GPS and GLONASS
http://stakeholders.ofcom.org.uk/spectrum/gps-jamming-exercises/1909141. However as this is UHF (line of sight) and the jammer at airborne but some distance away I expect an aluminium cone around the GPS antenna would cut out everything except the satellites above a certain altitude and you could still get a fix while there were 4 of them within the cone. [Edited after I read the link and found the jammer was airborne]
 
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lw395 said:
AFAIK, the major reason for wanting Glonass in a product is that the Russians get all stampy-feet about type approving anything that only has GPS.
Click to expand...

Well with GPS+GLONASS you get more satellites (so better precision) in mid latitudes and GLONASS gives much better accuracy in higher latitudes. Glonass also has an improvement programme that will improve accuracy globally. So stamp your feet all you like about this Putin, we will benefit from more dual standard devices.
 
lw395 said:
AFAIK, the major reason for wanting Glonass in a product is that the Russians get all stampy-feet about type approving anything that only has GPS.
Click to expand...

That's the reason it gets added, but it does provide a benefit for us in the form of redundancy against many (but not all) kinds of GPS problem.

Pete
 
Bi111ion said:
Just to confirm MOD GPS jamming exercises do jam the frequencies used by GPS and GLONASS
http://stakeholders.ofcom.org.uk/spectrum/gps-jamming-exercises/1909141. However as this is UHF (line of sight) and the jammer at airborne but some distance away I expect an aluminium cone around the GPS antenna would cut out everything except the satellites above a certain altitude and you could still get a fix while there were 4 of them within the cone. [Edited after I read the link and found the jammer was airborne]
Click to expand...
You'd do better with a directional antenna with a decent null pointed at the jammer. Perhaps.
Your ali cone would have to be pretty big I suspect.
I think it's easier to do dead reckoning than get an adaptive null steering EW rig to work on my boat?
 
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