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Old 3-Nov-2019, 1:39 AM   #2
Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,709
Testing the SiliconDust HDHR4-2US Connect Duo Tuner

After making the chart above, I started to wonder about the accuracy of the signal strength readings given by the HDHR tuner. I have never used an HDHR tuner, so I ordered an HDHR4-2US Connect Duo to make some tests.

When it came, I connected it to my Windows 7 laptop with a network cable. I went to which told me there wasn't a tuner connected, so I couldn't immediately download the software. I then went to the SD website and downloaded the software. I still wasn't able to connect until I entered the correct IP address in my network adapter and changed settings in my Norton software. I'm not a software expert, so this was becoming much more difficult than turning on a TV and going into the menu.

I set up the tuner and my 32" Sony TV with a splitter so that I could compare tuner sensitivity and signal readings. I picked my strong channel 33 to check the 100% signal strength reading of the HDHR and my marginal channel 9, that has just barely enough SNR above the noise, as test signals.

My 32" Sony KDL32R400A is a little different than most other Sony models. Its signal strength indicator goes all the way up to +41 dBmV (-8 dBm) at 100% instead of maxing out at 0 dBmV for 100% as most other TVs. Each step on the scale is one dB and I calibrated it with my signal level meter so that it can be used for tests like this.

I adjusted a step attenuator before the splitter so that the HDHR SS was 100%:
HDHR Signal Strength 100%, Signal Quality 98%
Sony TV SS 62 (+3 dBmV), SNR 28-29 dB

So the HDHR 100% was pretty close to 0 dBmV, considering my measurements aren't lab grade.

My marginal channel 9 signal looks like this; just barely enough SNR above the noise:

I adjusted the attenuator to make the signal weaker at the "Digital Cliff" to see which tuner would drop out first. To my surprise, the Sony tuner dropped out first; the HDHR tuner is more sensitive than I expected. It was still giving reliable reception at 50% Signal Quality.

At 49% Signal Quality, the Symbol Quality often dropped down into the red at lower readings:

and finally dropout:

Attached Images
File Type: jpg VHF-High Scan Gain 25.4 dB4.jpg (101.8 KB, 535 views)
File Type: jpg Channel 9A_1.JPG (126.1 KB, 1346 views)
File Type: jpg Channel 9B_1.jpg (103.2 KB, 1329 views)
File Type: jpg Channel 9C_1.jpg (112.4 KB, 1311 views)
If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 22-Nov-2019 at 6:17 PM.
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