TEST REPORTS FOR ZENITH/LG 5TH GEN PROTOTYPE AND LINX/MICRONAS PROTOTYPE:
Finally found the Test Reports for the Zenith/LG 5th Gen Prototype STB, the LINX (now Micronas) Prototype STB
plus a Field Test Report for the LINX Prototype STB compared to an older Harris ATSC STB (plus some Nokia COFDM STB equalizer tests):
1. Performance of 5th Generation 8-VSB Receivers, Laud, Aitken, Brett and Kwak,
IEEE Trans on Consumer Electronics, Vol 50, No 4, Nov 2004.
2. An ATSC DTV Receiver with Improved Robustness to Multipath and Distributed Transmission Environments,
Wu, Wang, Citta, et. al., IEEE Trans on Broadcasting, Vol 50, No 1, Mar 2004.
3. Results of the Lab Evaluation of Zenith 5th Generation VSB TV Receiver, Communications Research Center (CRC, Canada), Sep 2003.
4. Field Tests of the LINX ATSC Prototype Receiver, Communications Research Center (CRC, Canada), Mar 2003.
5. Recent Performance Improvements to the ATSC Transmission System, Su, Wang, Salehian, et. al.,
Intl Broadcasting Convention (IBC) Conference Pub 2003. See http://www.crc.ca/en/html/crc/home/r...broadcast/rtnt
6. Results of the Lab Evaluation of LINX ATSC Prototype Receiver, Communications Research Center (CRC, Canada), Apr 2002.
IEEE refs are available on-line (for a fee) or from a well-equipped (University) library.
The first IEEE reference had the all important link to CRC reports: http://www.broadcastpapers.com/tvtra...RCATSCTran.pdf
ATSC Doc A/74, Recommended Practice: Receiver Performance Guidelines, Jun 2004
says that a typical channel impulse response ranges from -10 us (pre-echo) to +40 us (post-echo).
A/74 then goes on to provide an Echo Delay performance profile for Single Static Echoes with various Desired to Echo Ratios:
from 0 to +5 us (for D/E > 1 dB) [Note: 0 dB Echo is not stipulated.]
from -5 to +10 us (for D/E > 2 dB)
from -5 to +20 us (for D/E > 3 dB)
from -10 to +40 us (for D/E > 5 dB) [The typical response cited above.]
from -20 to +40 us (for D/E > 7.5 dB) [Suggested Extension]
from -25 to +50 us (for D/E > 16 dB) [Suggested Extension]
So A/74 expects the typical impulse response to have a D/E > 5 dB and the so-called 0 dB Echo
or equal strength signals are expected to have a fairly small delay.
And extremely long pre-echo or post-echo signals would be at a much lower level than the desired signal.
[Indeed, if the echoes are much more than a D/E of 16 dB, they could be expected to cause minimal if any degradation.]
So how well did the Zenith/LG 5th Gen and LINX/Micronas Prototypes perform?
The LINX prototype was better than the LG prototype for all except the last test:
a. Random Noise: LINX C/N was 0.4 to 0.8 dB lower. LG worse at Weak signal levels.
b. Burst Noise: LINX sustained slightly wider pulse widths.
c. Brazil A thru E Test Ensembles: LINX C/N was a few tenths to several dB better.
d. Strong Static Echoes: LINX C/N was much lower for ACATS #286 and
Modified Brazil C/D test profiles.
e. Single Dynamic Echoes with increasing Doppler Rates: LG was better for two test
conditions, but failed for another two. LINX was better for four test profiles
and did not fail any.
f. Susceptibility to Dynamic Echoes in Presence of Random Noise: As expected,
LINX failed the CRC #3 and #4 profiles due to 35 us Echo exceeding equalizer
capability. However, for CRC #1 and #2, the LINX could tolerate D/E
approaching 0 dB, whereas the LG could not.
g. Single Echo Affecting Pilot: LINX passed. LG could not handle without errors.
h. Single Echo Test (parens denote whether it meets A/74 Guidelines or not).
Note that while the LG prototype was significantly better than the LINX prototype,
NEITHER unit met all of the A/74 Guidelines during this last test:
D/E = 10 dB -48.5 to +49.5 us for LG (yes) and -29.5 to +38.5 us for LINX (close)
D/E = 6 dB -24.0 to +25.5 us for LG (no) and -9.0 to +28.5 us for LINX (no)
D/E = 3 dB -13.0 to +13.0 us for LG (no) and -11.0 to +12.0 us for LINX (no)
D/E = 0 dB LG: not working and LINX: no test entry
Other performance Guidelines from A74:
i. Sensitivity: -83 dBm [Hence Noise Figure ~ 7 to 8 dB.]
Zenith/LG was -78.4 dBm, which does not meet A/74 Guidelines.
LINX not tested.
j. Max Input: -8 dBm (for each of multiple input signals)
Zenith/LG was -2.3 dBm for single input, multiple inputs not tested.
LINX not tested.
k. DTV Co-Channel D/U (at -68 and -53 dBm): +15.5 dB
Not tested. [LG may have problems meeting this test, see results for a. above.]
l. NTSC Co-Channel D/U (at -68 and -53 dBm): +2.5 dB
Zenith/LG was +3.1 dBm, which does not meet A/74 Guidelines.
LINX was +3.9 dBm, which does not meet A/74 Guidelines.
m. NTSC Adj-Chan D/U: -40 dB (at -68dBm), -35 dB (at -53 dBm), and -26 dBm (at -28 dBm)
Zenith/LG was -41.8 (at -68 dBm) and -42.0 dBm (at -53 dBm), meets A/74.
LINX was -43.7 (at -68 dBm) and -39.9 dBm (at -53 dBm), meets A/74.
n. DTV Adj-Chan D/U: -33 dB (at -68dBm), -33 dB (at -53 dBm), and -20 dBm (at -28 dBm)
Based on these tests, if you don't need extremely long pre and post-echo performance,
the LINX/Micronas prototype clearly had better overall performance.
And when Zenith/LG claims +/- 50 us equalizer capability,
they must mean when the Echo is 10 dB or more below the Desired signal.
Note they avoided mentioning performance for A/74 stipulated typical condition (D/E = 5 dB),
because both units failed to meet that guideline.
So it is impossible to compare manufacturer equalizer "claims" unless they also stipulate the test conditions!!!!
Of course, performance for production units may be different.