Anon 200D Dual ADC Use

yack9
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Joined: Sat Jun 24, 2017 7:24 pm

Anon 200D Dual ADC Use

Postby yack9 » Sat Jun 24, 2017 8:39 pm

I'm curious as to the second ADC function and how it works. Everything is currently on ADC 1. When I switch to 2, or fire up RX2 using 2, even on the same frequency and mode, the received signal is lower. Is this mormal or possibly something wrong with my rig? I have never seen an in depth tutorial on this subject. I'm currently running Open HPSDR mRX PS 3.4.1 and Orion firmware 4.9. This is the one thing that has me confused about this rig.
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w-u-2-o
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Re: Anon 200D Dual ADC Use

Postby w-u-2-o » Sun Jun 25, 2017 1:01 am

If you look at the block diagram in the user guide, you will see that ADC1 is fed exclusively from ANT1, 2 or 3 on receive, and that ADC2 is fed exclusively from the input connector on the back of the radio marked "RX2" on receive. This is also true for the 100D. On the 8000 the ADC2 connector is marked "ADC2".

The rear panel connector labeling on the 100D and 200D can be a bit confusing because in the software RX2 can be assigned to either ADC1 or ADC2 (Setup > General > ADC). That is why the rear panel connector labeling was changed on the 8000. However, for purposes of this discussion, let's assume that you have RX2 assigned to ADC2.

Under those conditions you must have a separate antenna attached to the RX2 input. If that antenna does not have precisely the same characteristics as the main antenna that is assigned to RX1 then obviously the signals will look and sound different on each receiver.

You can do a lot of things with ADC2. The most popular thing is to configure a second antenna and then coherently combine them in so-called "diversity" mode, really coherent beamforming. This can be used to either null out a noise source in a particular direction, or improve gain in a particular direction (or, if you are really lucky, both at the same time). Note this cannot reduce your noise floor, as that sort of noise is incoherent and random, but it can potentially null out an interfering signal.

Perhaps the most mundane thing to do with ADC2 is to use it to monitor a second band using a separate antenna.

You can also use it with different antennas to effect amplitude, polarization and other forms of non-coherent, spatial diversity.

73,

Scott
yack9
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Joined: Sat Jun 24, 2017 7:24 pm

Re: Anon 200D Dual ADC Use

Postby yack9 » Sun Jun 25, 2017 4:12 am

Thank you very much. That cleared things up for me. I think I'm going to play with the diversity reception.

73
N8UMW
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w-u-2-o
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Re: Anon 200D Dual ADC Use

Postby w-u-2-o » Sun Jun 25, 2017 9:56 am

a61ek
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Re: Anon 200D Dual ADC Use

Postby a61ek » Tue Dec 05, 2017 1:21 am

Hi

If i connected two antenna, Adc1 and adc2. While transmitting on adc1 is the adc2 is protracted by any sort or relay??

Will the DX Engineering Receiver Guard do the work??
Thanks
Omar
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w-u-2-o
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Re: Anon 200D Dual ADC Use

Postby w-u-2-o » Tue Dec 05, 2017 1:23 pm

Omar,

It depends on the radio. Some radios have a user configurable ground--on-TX relay on ADC2. You could make a mistake.

A DX Engineering limiter ("Receiver Guard") will provide good protection under most circumstances. I use one here as "cheap insurance", and because sometimes I like to receive off the air while I transmit to check antenna performance.

73,

Scott
a61ek
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Re: Anon 200D Dual ADC Use

Postby a61ek » Wed Dec 06, 2017 1:46 am

Thanks Scott..iwill order one very soon...

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