The question that a lot of users seem to have on their mind is "What benefits, if any do I get by using ICOMS DPD in conjunction with a Solid State Power Amplifier (SSPA)"
Well, I measured a 6dB improvement.
Measurement setup:
- SPECAN: SDR-IQ
- TAP: VK5HW (50dB)
- ATT: 20dB
- PWR: 1000W
- ANT: Dummy Load (RL 28.3dB)
- Software: SpectraVue V.3.44 Beta 0
DPD off
Two tone test:
Result:
1st Value -31.311dBc
2nd Value -31.455dBc
3rd Value -52.398dBc
4th Value -53.545dBc
IM Max -22.2dBc
IM Avg -21.6dBc
NOTE: 1st and 2nd value are the two tones (fundamentals) and 3rd and 4th value are IM3.
Look at IM3 and IM5, they are nearly the same in strength.
And the below using my Voice Caller calling CQ:
1st Value -23.996dBc
2nd Value -31.168dBc
3rd Value -49.526dBc
4th Value -53.689dBc
IM Max -29.7dBc
IM Avg -24.0dBc
DPD ON
Two tone test:
Result:
1st Value -31.168dBc
2nd Value -31.311dBc
3rd Value -58.996dBc
4th Value -59.139dBc
IM Max -28.0dBc
IM Avg -27.8dBc
Well, we do see about a 6dB improvement on the two tone test which is better than a Mosquito fart. But I believe the below is quite a good example on how well it improves your VOICE signal!
And below, using my Voice Caller calling CQ:
Result:
1st Value -20.840dBc
2nd Value -27.582dBc
3rd Value -57.750dBc
4th Value -60.143dBc
IM Max -39.3dBc
IM Avg -34.7dBc
On average we see an improvement of 7dB again better then a Mossi fart.
So I'd say any reduction in IMD, and be it only 6dB, is an improvement. As such, I would recommend enabling DPD whilst using an RF-Amplifier however, YMMV ....
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