Reverse Loss Planning & RSL Range

[marcknapp]

Hi All. First post, here. I'm an RF engineer in the cellular space and have been dipping my toes into some use cases for GMRS for some local relay trail runs as a hobby. I am specifically looking for information on the receiver RSL range for some of the more common H/Ts like the KG-805G or the KG-UV6D. Since any link that has an HT in it will always be reverse link limited, I am surprised by the lack of published information on this.

 

For cellphones as an example, most are capable of an RSSI range of -30 dBm to -110 dBm depending on the SINR. What I cannot find is: a) general guidance on that for GMRS (or even something close in the HAM bands) or any specific information from the Wouxun page on the actual range for the 805G or the UV6D. I need this to determine my coverage levels in my propagation tool, Atoll. I've built the sites in the software and have run the predictions for my locations, but without understanding the minimums and related SNR, I can't set my thematic maps precisely enough for a good idea of where my limits will be. I'm currently set up with -95 dBm as that seems to be fairly reasonable, but my OCD doesn't like assumptions.

 

Thanks for any help!  

[gortex2]

In the radio world we use db for receive sensitivity. Looking at a cheap radio most dont publish this specification as they probaby dont know. Just a quick search on a bisiness UHF radio from motorola is -122 at 12db sinad. 

 

https://www.motorolasolutions.com/content/dam/msi/docs/business/products/two-way_radios/portable_radios/small_business_portable_radios/cls1410/_documents/static_files/cls_specsheet.pdf

 

The UV6D you mentioned is not an approved GMRs radio but its site does list the rx sensitivity as .16 microvolts. I'd have to go grab my service monitor to see what that is in db but guessing the -120 is close. 

 

https://www.buytwowayradios.com/downloads/dl/file/id/931/product/2566/wouxun_kg_uv6d_product_sheet.pdf

[mbrun]

Hi All. First post, here. I'm an RF engineer in the cellular space and have been dipping my toes into some use cases for GMRS for some local relay trail runs as a hobby. I am specifically looking for information on the receiver RSL range for some of the more common H/Ts like the KG-805G or the KG-UV6D. Since any link that has an HT in it will always be reverse link limited, I am surprised by the lack of published information on this.

 

For cellphones as an example, most are capable of an RSSI range of -30 dBm to -110 dBm depending on the SINR. What I cannot find is: a) general guidance on that for GMRS (or even something close in the HAM bands) or any specific information from the Wouxun page on the actual range for the 805G or the UV6D. I need this to determine my coverage levels in my propagation tool, Atoll. I've built the sites in the software and have run the predictions for my locations, but without understanding the minimums and related SNR, I can't set my thematic maps precisely enough for a good idea of where my limits will be. I'm currently set up with -95 dBm as that seems to be fairly reasonable, but my OCD doesn't like assumptions.

 

Thanks for any help!

The 805G Radio has published rated sensitivity of <.2uV (-121dBm) for 12dB SINAD, and a selectivity of 65dB. I found and downloaded the information from the Wouxun.com website last summer. Within the last week I was using a signal generator to determine the level at which the 805 broke squelch when squelch has set a 1. It started to open at -125dBm and was open solid at -123dBm. But, in all fairness, my meter is not calibrated so it could be off a few dB. Of course this does not mean that this is the level at which 12dB SINAD is reached.

 

 

Michael

WRHS965

KE8PLM

[JLeikhim]

Hi All. First post, here. I'm an RF engineer in the cellular space and have been dipping my toes into some use cases for GMRS for some local relay trail runs as a hobby. I am specifically looking for information on the receiver RSL range for some of the more common H/Ts like the KG-805G or the KG-UV6D. Since any link that has an HT in it will always be reverse link limited, I am surprised by the lack of published information on this.

 

For cellphones as an example, most are capable of an RSSI range of -30 dBm to -110 dBm depending on the SINR. What I cannot find is: a) general guidance on that for GMRS (or even something close in the HAM bands) or any specific information from the Wouxun page on the actual range for the 805G or the UV6D. I need this to determine my coverage levels in my propagation tool, Atoll. I've built the sites in the software and have run the predictions for my locations, but without understanding the minimums and related SNR, I can't set my thematic maps precisely enough for a good idea of where my limits will be. I'm currently set up with -95 dBm as that seems to be fairly reasonable, but my OCD doesn't like assumptions.

 

Thanks for any help!

GMRS is part of the LMR world so the propogation document I would refer you to is EIA/TIA TSB88C or D.

 

Radios in LMR typically comply with TIA603D as far as SINAD sensitivity, IM , spurious, and adjacent channel rejection . That document stipulates how LMR radios are tested and provides minimum standards.

 

The "Common" Chinese brand radios do not comply with any industry standards thus a receiver spec of "-122 dBm " is meaningless in the real world where stronger out of band signals will swamp the receivers of cheap radios that lack adequate front end filtering.

 

 

Sent from my SM-T350 using Tapatalk

[OldRadioGuy]

Why don't you just get a couple 805G's and test them.

They are about as good as you are going to get in a modest priced GMRS radio.

The next step up is a huge leap in price.

 

The antenna is a significant factor.

If you can sub a Nagoya 771 or a Smiley Super Stick things improve quite a bit. 

 

My experience is that my 80G's perform similarly to my Yeasu ham HT.

This is based on working repeaters 15-20 miles out.

 

I always find that terrain is the limiting factor with ground to ground comm on GMRS.

It's usually "all or nothing" so small changes in sensitivity wouldn't change much.

 

Vince