Analog vs Digital V1 Performance

**KnightHawk** · 07-26-2007, 09:23 AM

Obviously as we know, digital processing is faster than analog processing. Can anyone shed light as to what difference can it make between the 2 if there are any in performance, reliability, advantages and disadvantages?

Your thoughts guys.

**jimbonzzz** · 07-26-2007, 09:50 AM

The V1 has used "digital processing" ever since it's introduction, so I'll assume you're asking about the differences between the pre-3.851 V1's (QJAV18) with "analog temperature compensation" vs the 3.851 and later (QJAV18A) with "digital temperature compensation".

The most notable difference is the addition of the "digital temperature compensation board" in the QJAV18A. This board samples the first LO and divides it down so that it can ultimately be compared to a reference. Then, the 1st LO can be adjusted or "calibrated" accordingly. This is to compensate for temperature, and also components which might change value slowly over time ("aging").

The previous version QJAV18 w/ analog temperature compensation most likely used a negative temperature coefficient capacitor somewhere in the circuit, to compensate for the rest of the components which most likely have a positive temperature coefficient (where resistance rises with temperature).

I'm sure the analog method wasn't completely linear, so the new method would definitely work better in that respect. Since the oscillator basically stays calibrated, there probably isn't as much oversweeping to be sure the police radar bands are covered when the oscillator drifts during normal operation. Of course, this has a positive effect on performance, probably not a large difference though.

Another benefit: the new digital compensation makes it much easier for the V1 to recognise when there is a problem. For example, if components fail or age causing it to go out of tune beyond what it can adjust, it will know this and throw and "E". Although the previous units could sometimes throw an "E" under some conditions, they didn't have the ability to monitor the 1st LO directly like the new ones do.

ES13Raven · 07-26-2007, 09:59 AM

Is the difference something a regular user will see?

Probably not :wink:

**BullyDawg19** · 07-26-2007, 10:14 AM

are you saying that those with older versions should upgrade?

ES13Raven · 07-26-2007, 10:17 AM

Originally Posted by BullyDawg19

are you saying that those with older versions should upgrade?

A lot of people who "upgraded" because they wanted the latest and greatest, shot themselves in the foot. 3.851+ versions had problems with getting E errors and had to be sent back to VR.

Wait until new versions are stable. Don't be a beta tester. :wink:

**GTO_04** · 07-26-2007, 01:02 PM

And the digital temperature compensation versions are more easily detected by Spectre! They need to integrate that PC board into the horn assembly, but they will have to redesign the PC board to do that. Might as well make it Spectre immune at the same time. :wink:

GTO_O4

**TeamQuack** · 07-26-2007, 03:54 PM

Originally Posted by ES13Raven

Originally Posted by BullyDawg19

are you saying that those with older versions should upgrade?

A lot of people who "upgraded" because they wanted the latest and greatest, shot themselves in the foot. 3.851+ versions had problems with getting E errors and had to be sent back to VR.

Wait until new versions are stable. Don't be a beta tester. :wink:

lol

i caught myself in a pickle, i think my baby is going out of tune and i want it tuned up but not upgraded, can i do that or am i screwed :?

ES13Raven · 07-26-2007, 04:05 PM

Originally Posted by TeamQuack

i caught myself in a pickle, i think my baby is going out of tune and i want it tuned up but not upgraded, can i do that or am i screwed :?

You are fine... the upgrade is a hardware upgrade so VR charged people $80 I believe. If you are sending in for a tune-up, you will get back 3.826 - which is a great version!

**KnightHawk** · 07-26-2007, 05:51 PM

Originally Posted by jimbonzzz

The V1 has used "digital processing" ever since it's introduction, so I'll assume you're asking about the differences between the pre-3.851 V1's (QJAV18) with "analog temperature compensation" vs the 3.851 and later (QJAV18A) with "digital temperature compensation".

The most notable difference is the addition of the "digital temperature compensation board" in the QJAV18A. This board samples the first LO and divides it down so that it can ultimately be compared to a reference. Then, the 1st LO can be adjusted or "calibrated" accordingly. This is to compensate for temperature, and also components which might change value slowly over time ("aging").

The previous version QJAV18 w/ analog temperature compensation most likely used a negative temperature coefficient capacitor somewhere in the circuit, to compensate for the rest of the components which most likely have a positive temperature coefficient (where resistance rises with temperature).

I'm sure the analog method wasn't completely linear, so the new method would definitely work better in that respect. Since the oscillator basically stays calibrated, there probably isn't as much oversweeping to be sure the police radar bands are covered when the oscillator drifts during normal operation. Of course, this has a positive effect on performance, probably not a large difference though.

Another benefit: the new digital compensation makes it much easier for the V1 to recognise when there is a problem. For example, if components fail or age causing it to go out of tune beyond what it can adjust, it will know this and throw and "E". Although the previous units could sometimes throw an "E" under some conditions, they didn't have the ability to monitor the 1st LO directly like the new ones do.

Sorry for not making it clear but i was talking about the pre 3.851 vs 3.851 and up. Thank you very much jim for bringing up the difference between the 2 and that helps me a lot just to know the difference.