Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Jim Wilkens]

I'm trying to get better results with my TTi analyser.
The noise floor reads around -95dB on the TTi but -75 when I import it into WWB.
Also reads -75dB in IAS.
I've set RBW to 15KHz, Ref. to -20dB, Span to 60MHz.
The TV channels look very week when viewing in WWB and IAS.
Any tips or settings I am missing?

Thanks,
Jim Wilkens

[Russell Ault]

I'm trying to get better results with my TTi analyser.
The noise floor reads around -95dB on the TTi but -75 when I import it into WWB.
Also reads -75dB in IAS.
I've set RBW to 15KHz, Ref. to -20dB, Span to 60MHz.
The TV channels look very week when viewing in WWB and IAS.
Any tips or settings I am missing?

I'm not familiar with the TTi's operation in particular, but I've got some general thoughts:

First, is there a relationship between your Ref being set to -20dB and your measurements importing 20dB up? Does it look correct in WWB with Ref set to 0?

Second, for the TV stations, judging by the relative height of other peaks (many of which appear to roughly match), I'd guess that you're seeing a combination of two things: the difference in antenna and placement between the ULXD system and the analyzer (is there a reason the ULXD's selected antenna might be receiving TV stations more strongly?), and the apparently low resolution of the CSV file (which, despite setting a RBW of 15kHz, appears to be closer to one data point every 500 kHz or so).

To check for the antenna difference you can try adapting the TTi's input to plug into your antenna distribution; as good practise, always use at least a DC blocker when doing this unless you're positive your analyzer has one built in (I'd recommend an RF power limiter too, just in case). For the data resolution, open up the CSV file in a text editor and see how the data looks; I'm guessing that, for whatever reason, your file doesn't have anything close to one data point for every 15kHz (although why I couldn't say).

-Russ

[John Sulek]

I'm trying to get better results with my TTi analyser.
The noise floor reads around -95dB on the TTi but -75 when I import it into WWB.
Also reads -75dB in IAS.
I've set RBW to 15KHz, Ref. to -20dB, Span to 60MHz.
The TV channels look very week when viewing in WWB and IAS.
Any tips or settings I am missing?

Thanks,
Jim Wilkens

Not sure if the "average" mode for the trace would help with this. I usually set it to at least 4 sweeps.
I use the same rbw, ref and span settings and the noise floor tracks on WWB and IAS. Just tried a few files to double check. There is a download of TTi settings up on the Best Audio site. <www.bestaudio.com>

To answer Mr Ault, the -20 ref setting is TTi's way of saying the rf input attenuator is off.
And the csv file is 271 data points for a 60Mhz span so roughly 221kHz between points. You could reduce the span for more detail, but that setting captures iem and BTR tx spikes as well as HH and bodypack tx. Gives you a pretty good idea where to zoom down to.

One tip is to set the scale to 5db per division to make stuff easier to see on the TTi screen but that doesn't affect the stored traces from trying it both ways.

Sorry I can't better answer your question.

[Jim Wilkens]

Thank you Russ. I did use the same whip antenna located in roughly the same location into both the ULXD and the TTi. Also, tried the antenna distribution system into the TTi.

I did not use a DC blocker - didn't think of that. Perhaps I damaged it but the trace looks pretty normal on the TTi.

Other questions answered below. I'm using settings recommended by Pete Erskine. 60MHz span recommended to get enough resolution in the exported csv. I could try going narrower but it seems like it's the magnitude that's the problem.

I'm not familiar with the TTi's operation in particular, but I've got some general thoughts:

First, is there a relationship between your Ref being set to -20dB and your measurements importing 20dB up? Does it look correct in WWB with Ref set to 0?

Second, for the TV stations, judging by the relative height of other peaks (many of which appear to roughly match), I'd guess that you're seeing a combination of two things: the difference in antenna and placement between the ULXD system and the analyzer (is there a reason the ULXD's selected antenna might be receiving TV stations more strongly?), and the apparently low resolution of the CSV file (which, despite setting a RBW of 15kHz, appears to be closer to one data point every 500 kHz or so).

To check for the antenna difference you can try adapting the TTi's input to plug into your antenna distribution; as good practise, always use at least a DC blocker when doing this unless you're positive your analyzer has one built in (I'd recommend an RF power limiter too, just in case). For the data resolution, open up the CSV file in a text editor and see how the data looks; I'm guessing that, for whatever reason, your file doesn't have anything close to one data point for every 15kHz (although why I couldn't say).

-Russ

[Jim Wilkens]

Thank you, John. I used the settings recommended on the Best Audio site. The trace looks OK on the TTi but just very low res in the vertical on both WWB and IAS. I tried subtracting 20db from the entire csv file and that moved my noise floor down to even with the ULXD scan but the signal was still low. Again, using the same antenna for both.

Not sure if the "average" mode for the trace would help with this. I usually set it to at least 4 sweeps.
I use the same rbw, ref and span settings and the noise floor tracks on WWB and IAS. Just tried a few files to double check. There is a download of TTi settings up on the Best Audio site. <www.bestaudio.com>

To answer Mr Ault, the -20 ref setting is TTi's way of saying the rf input attenuator is off.
And the csv file is 271 data points for a 60Mhz span so roughly 221kHz between points. You could reduce the span for more detail, but that setting captures iem and BTR tx spikes as well as HH and bodypack tx. Gives you a pretty good idea where to zoom down to.

One tip is to set the scale to 5db per division to make stuff easier to see on the TTi screen but that doesn't affect the stored traces from trying it both ways.

Sorry I can't better answer your question.

[ClintonH]

I'm trying to get better results with my TTi analyser.
The noise floor reads around -95dB on the TTi but -75 when I import it into WWB.
Also reads -75dB in IAS.
I've set RBW to 15KHz, Ref. to -20dB, Span to 60MHz.
The TV channels look very week when viewing in WWB and IAS.
Any tips or settings I am missing?

Thanks,
Jim Wilkens

Hi Jim. I know it's been a little bit since you posted this so maybe you found the answer already but it seems like the firmware of the TTI is the culprit. I was still on v1.x and never thought to check in to upgrade it. Well it's on 2.03 now.

One of the bug fixes was for trace file data:

"Earlier versions of the PSA Series 2 (prior to version 1.x) stored trace file data in a format
where the trace amplitude values were relative to the Reference level. This has been changed
in version 2.x so that the values are absolute. This can be important when using the files for
external applications.

PSA Manager version 2 automatically recognizes which format is being used. However, third
party programs which were adapted to use the previous relative format may now give incorrect
results. In these cases, the original format can be used by selecting “Relative to Ref.” from the
pop-up menu within the “Prefs.” function of the System Utilities menu"


This solved this WWB import level issue. So lesson here is, always check firmware/software version. 

[Mac Kerr]

Hi Jim. I know it's been a little bit since you posted this so maybe you found the answer already but it seems like the firmware of the TTI is the culprit.

Please go to your profile and change the "Name" field to your real first and last name as required by the posting rules displayed in the header at the top of the section, and in the Site Rules and Suggestions in the Forum Announcements section, and on the registration page when you registered.

Mac
admin

[ProSoundWeb Community]