H21-200 {CE:12:05a} 0x4314 - Issues Only

Discussion in 'DIRECTV - H2x Discussion (private)' started by Stuart Sweet, Aug 22, 2008.

Did you receive the push?

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  2. NO - Please describe

    9 vote(s)
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  1. hasan

    hasan Well-Known Member

    Sep 22, 2006
    Ogden, IA
    OK...here are the numbers. (percent on the signal meter, showing bit-error-rate derived measurement)

    Channel AM21/H21/Indoor AM21/HR21/Outdoor HR20/Outdoor

    5-1 71 92 93-B

    8-1 92 93 90-B

    11-1 100 100 100

    13-1 85 100 100

    17-1 52 84 84

    23-1 82 94 84-B


    A "-B" suffix indicates considerable "bounce" symptomatic of multi-path issues.

    All transmitting antennas are at the same location, elevation 2200 feet. Distance is approximately 28.7 miles at a bearing of 138 degrees.

    Indoor Antenna = Philips MANT510 (UHF Plate + Rabbit Ears), 4 dB Noise Figure
    Outdoor Antenna = CM medium sized VHF/UHF combo at 32' (roof top)

    All my stations are currently UHF, so the Telescoping Rabbit Ears are fully collapsed, vertical, and parallel to the UHF plate. The preamp off/on produces a 30% signal improvement on the H21/AM21 combo, with a gain setting of 4 out of 5 LEDs.

    Summary Conclusions:

    1. Notice only the HR20 OTA tuner shows significant bounce (even on the same outdoor antenna, signal level balanced between the HR21 and HR20). This demonstrates better multi-path resistance of the AM21 tuner. (confirmed from prior measurements)

    2. Notice even on an antenna that cannot discriminate effectively against multi-path (Phillips MANT510), the AM21/H21 combo shows no significant bounce. This is outstanding performance.

    BTW, this indoor antenna is available at Wal-Mart for around 29 bucks. It is labeled Philips, 50 dB gain and is all silver. (the gain is not important, look on the side panel for its Noise Figure..it should say 4 dB)

    All in all, the tuner performance of the AM21 is terrific, both on the HR21 and the H21, even with a very modest, but well designed, antenna (in this area, at this distance).
  2. Altcool

    Altcool Legend

    Jun 11, 2007
    I was away from my home for the last five days I checked my H21 today and it still has the 430c software with a download date of 8/8/08.
  3. texasbrit

    texasbrit Well-Known Member

    Aug 9, 2006
    I repeated your test with some interesting results. First, I am using an SWM8 with diplexing; both the HR20-700 and HR21/AM21 are driven from a four-way splitter (I have an HR20-100 and an H20-600 on the other legs). I am about 42 miles from the DFW transmitter "farm" at Cedar Hill, using a CM4228/CM7777 combination.
    I have 16 digital OTA stations (plus subchannels).
    On my weakest stations the additional sensitivity (or multipath rejection, or both)of the HR21 is very noticeable. One station will not come in at all on the HR20, I get mid-60s with the AM21. Of course my lack of signal on the HR20 could be multipath, it's difficult to know. Typically all my weaker stations (60s to 70s) show four or five more points on the AM21 than they do on the HR20. All the stations (except those with close to 100 on the signal meters) show significantly more fluctuation on the HR20 than on the AM21 - 6 to 8 points on the HR20 compared with 1 or 2 on the AM21.
    Interestingly, on several of my stations where the signal fluctuates a lot on the HR20 the peak reading on the HR20 is higher than on the AM21. For example, channel 23-1 on my HR20 fluctuates from 74 to 88. On the AM21 it is virtually rock steady at 76/77. Similarly 8-1 (my only VHF station, on actual channel 9) has a range of 79-92 on the HR20 and 85-86 on the AM21.

    Just for interest I checked my HR20-100 and my H20-600. The HR20-100 showed readings that were essentially the same as the HR20-700. The H20-600 was noticably better than the HR20s but not quite as good as the AM21 - it received my one very weak station with a signal meter reading in the high 50s. It also showed the same signal chacteristics as the AM21 on the "fluctuating" stations - more stable than the HR20 but with lower peak/average signals.
    Of course the AM21 has an internal signal splitter like the HR20s (even though you are only using one tuner when you are connected to the H21) so the H20-600 has a 3db advantage. That gives even more kudos to the AM21's performance.
  4. hasan

    hasan Well-Known Member

    Sep 22, 2006
    Ogden, IA
    Outstanding job! I'm both amazed and heartened at the near 100% correlation between your measurements and mine...even to the point of finding one signal (or more) that had a raw reading slightly higher on the HR20 (but with much more bounce), than on the AM21. Here is what I have noticed and what I would predict will continue to happen if you observe this particular case on the HR20. Eventually,. you will see momentary, but profound variations in bit-error-rate, something on the order of 30 percentage points or more. I let mine run for about 10 minutes, watching the bounce all the time, and on several occasions the HR20 signal went from the high 70's with bounce, down to 30 or 34 percent for a second or two, resulting in loss of picture. The AM21 didn't show any such deviations.

    Thanks so much for replicating the experiment, as it is important to check for "one of" results. Not that we are publishable, but it does add credibility to the claimed assessment of the AM21 tuner being clearly superior to the HR20 series. (and we can dismiss the 3 dB splitting issue, as I have already controlled for that in another experiment directly comparing the AM21 to the HR20 and varying the signal level in small increments, both favoring and not favoring the HR20.)

    No difference in results was noted.

    Some brief, but interesting measurements shows the performance of the AM21 tuner is superior to the tuner in my Sanyo 37" HDTV (LCD). This is the first D* OTA tuner that could outperform ANY internal HDTV tuner that I have. I got the HR20 to actually match the performance of my Samsung HL-R5667W, but it took 4 hours of tweaking gain distribution, attenuation and line length, where as the AM21 exceeded the Sanyo right out of the shoot.

    Good news, this AM21 tuner. Very good news. Thanks again for taking the time to check my results, it is much appreciated (even if only by you and me):)
  5. xzi

    xzi Icon

    Sep 18, 2007
    On vacation this week, don't know if I got this yet. I had reverted to NR a few weeks ago with that HDMI issue.
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