[NLRS] GPS and RTK

[Dr. Gerald N. Johnson]

The RTK base station receives only GPS and transmits at the other band, 
at least that's how the VHF and UHF versions work. The GPS receiver 
might not take well to 1296 close by.

As an EME station you have a receiver MDS better than -145 dBM and the 
preamp probably doesn't have very much front end selectivity, the lowest 
noise preamps lack that front end selectivity because good selectivity 
has insertion loss to raise the NF. A 1 watt transmitter is +30 dBM, 175 
dB or 500,000,000 times stronger than the desired signal at the noise 
level received signal. If the receiver can hack that it might be OK, but 
its likely the transmitter PA puts out some broadband noise, maybe only 
100 dB (for a really fine transmitter) down but more likely only 80 dB 
or less down that can add to the ham band noise level.

My answer to the request would be that the potential disturbance to my 
receiving from the RTK transmitter would destroy my weak signal 
performance and that I can't tolerate. I moved to the country to get 
away from noise sources, that would bring it to me. And mention that the 
transmitter at 1 watt would be half a billion times stronger than the 
signals I receive off the moon. The RTK is as beneficial to my ham radio 
operating as planting crop in the middle of the Missouri River. It sure 
gets water but more water than it can stand.

73, Jerry, K0CQ

On 6/13/2014 6:45 AM, Jon Platt via NLRS wrote:
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> One more consideration.  Coexistence.  So you need to consider not only interference that RTK may cause to your ARS operation, but what interference does your ARS cause to RTK.   The concern is that the RTK system would be physically located close to your HF/VHF antennas.  Even low band operations may generate enough RF field strength to swamp VHF/UHF RF front ends and/or get into any digital electronics via power lines, etc, and cause blocking, device reset, erratic operations, etc.  Just ask my XYL about her TV when I am on 10 MHz.
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> This may also be a nice way for you to save face with your neighbor ..... "I would like to help but because the RTK system is physically located so close to my transmitting antennas it would probably cause the RTK to not work like you need it too.  You would end up spending lots of money and it won't work".
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> 73, Jon
> W0ZQ
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> Register for the CSVHFS conference on July 25-26th at:
> http://www.csvhfs.org/2014conference/index.html
>
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