Bad OpenSpot RX-Sensitivity

dl5dae
Posts: 6
Joined: Thu Oct 20, 2016 2:59 pm

Bad OpenSpot RX-Sensitivity

Post by dl5dae »

Hello together,

we have here a new problem with the RX-Sensitivity, we test it with 5 units, with the same results, very short distance from OpenSpot to a handheld TRX!!
OpenSpot with the original antenna, also with other SMA-Antennas.

Freefield-Test:
Test-1: 100mW TX-Power DSTAR distance 50m
Test-2: 100mW TX-Power DMR max. distance 25m
Test-3: 100mW TX-Power C4FM max. distance < 15m!!!

Inhouse-Test:
C4FM: We don’t can TX work outside the same room!!!
DMR: one room better
DSTAR: Inhouse OK, Outside in the garden max. +15m around the house.

Modem-Settings/Setting like factory.

73 de DL5DAE, Erik

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g8koe
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Joined: Sun Sep 04, 2016 8:33 pm

Re: Bad OpenSpot RX-Sensitivity

Post by g8koe »

Hi Eric,
My openSpot exceeds your finding.
All hotspots use a very basic receiver that can be prone to local RF interference. As you can’t use the openspots around your house would suggest possible interference problem. There are many possible sources of interference Phone mast and energy saving lamps being very common.
Have you tried different frequencies?

73’s
Martin
G8KOE

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HA2NON
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Re: Bad OpenSpot RX-Sensitivity

Post by HA2NON »

Hello,

openSPOT is configured to low sensitivity with high linearity for lowest BER by default. You can increase the sensitivity on the modem page (you have to turn on advanced settings).
Norbert "Nonoo" Varga, HA2NON
SharkRF Team

DL7DW
Posts: 13
Joined: Sat Oct 29, 2016 8:47 am

Re: Bad OpenSpot RX-Sensitivity

Post by DL7DW »

I am writing this on behalf of DO5DS, Dieter, because his English skills are limited.
The sensivity issue still exists, Norbert. The openspot still limits the range of movement in the users environment. As my friend Eric (DL5DAE) mentioned before, the tests were performed by 5 Ham's testing the openspot. All with the same outcome! We probably would have never ever noticed that problem. It turned out by accident when we tested with Frank, DJ7FG the openspot while he was using his FTM400 connected to a roof antenna and transmitting with 25 watts! The openspot couldn't hear him! So all the others started testing the receive-range of the spot and everybody adjusted the sensivity in the advanced settings with no real result. The advanced sensivity settings seemed to cure the issue a little bit but compared to many other spots the openspot still appears to suffer from a remarkable receive limitation. Another example, Dieter walked out of his shack, through the kitchen to his garage, distance not more then 8m, two walls between him and his openspot! In front of the garage he turned around and I could clearly hear bit errors right in that moment when his back faced towards the open spot. We performed several tests all with the same results. So after these tests Dieter updated the openspot to the newest beta firmware in hope that this update might solve the issue. Unfortunately nothing changed.

Regards and many thanks for your efforts
Andreas/DL7DW

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HA2NON
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Re: Bad OpenSpot RX-Sensitivity

Post by HA2NON »

Interesting, as all my units work great around the house in the 432-436 MHz band. Have you tried changing frequencies and enabling the AGC? We'll look at the issue anyway.
Norbert "Nonoo" Varga, HA2NON
SharkRF Team

dl5dae
Posts: 6
Joined: Thu Oct 20, 2016 2:59 pm

Re: Bad OpenSpot RX-Sensitivity

Post by dl5dae »

Hello,

i have make new test’s with the sensitivity-level choose: Nr .1 
Now it is for me OK, the Spot ist with the factory antenna in the basement
of my house and in all areas outside in the garden the test was 100% with
 D-STAR & DMR. (C4FM today no testing.)

73 der Erik DL5DAE

dmlad4uu
Posts: 19
Joined: Thu May 12, 2016 12:33 pm

Re: Bad OpenSpot RX-Sensitivity

Post by dmlad4uu »

Hello all,

I too would like to see the receive improved on the Openspot. i have a 8 watt amp that works very well.
I can hear the Openspot 6 miles away. The problem is I can only get in from about 1 1/2 miles away.
And it doesn't matter if I use 5 watts or 45 watts. That is it.

Any plans to improve the receive?

Thanks

Dave/AD4UU

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HA2NON
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Re: Bad OpenSpot RX-Sensitivity

Post by HA2NON »

Hello Dave, openSPOT is mainly designed for home use only (indoors, around the house).
Norbert "Nonoo" Varga, HA2NON
SharkRF Team

pa3bas
Posts: 26
Joined: Sat Aug 20, 2016 8:43 am

Re: Bad OpenSpot RX-Sensitivity

Post by pa3bas »

If you use openspot with several users you have two problems:

- openspot isnt a true repeater, so you hear your friend directly, not through openspot.
- if you transmit 5 watt with your handheld you could desensitize other receivers close to your frequency.

Are you sure this is not the Case with you Guys?


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CoraDias
Posts: 1
Joined: Mon Mar 19, 2018 6:07 pm

Re: Bad OpenSpot RX-Sensitivity

Post by CoraDias »

Hi...i am a new user here. As per my knowledge the advanced sensivity settings seemed to cure the issue a little bit but compared to many other spots the openspot still appears to suffer from a remarkable receive limitation. Another example, Dieter walked out of his shack, through the kitchen to his garage, distance not more then 8m, two walls between him and his openspot! In front of the garage he turned around and I could clearly hear bit errors right in that moment when his back faced towards the open spot.

printed circuit board
Last edited by CoraDias on Thu Apr 12, 2018 8:13 pm, edited 1 time in total.

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