drmpeg

17 ms·

151.
by drmpeg 3y ago
I liked "Nope" more.
152.
by drmpeg 3y ago
Even after 3 years, I'm still sad about Clarke's Charcoal Broiler in Mountain View.
153.
by drmpeg 3y ago
I guess a few people got the board to do something useful, but the vast majority of Parallella boards are sitting in a box in the bottom of a closet somewhere.
154.
by drmpeg 3y ago
There was a "strong" product, the Beagleboard X-15. It came out before the Pi4 and had better performance than a Pi3B. However, it was on the expensive side at over $200.
155.
by drmpeg 3y ago
With less error coding (13/15 code rate), the constellation is more rectangular. https://www.w6rz.net/64qamnuc1315.png With really heavy error coding (2/15 code rate), the constellation becomes almost unrecognizab
156.
by drmpeg 3y ago
On the technical side, the patent is for Non-Uniform Constellations or NUCs. It's a modification of the modulation constellation points to match the error coding. Traditional 64QAM: https://www.w6rz.net/64qamrect.png A
157.
LG halts production of ATSC 3.0-compatible TVs over patent concerns(lightreading.com)
3 points by drmpeg 3y ago|2 comments
158.
by drmpeg 3y ago
"This challenging and uncertain patent landscape has forced LG to make the difficult decision to suspend the inclusion of ATSC 3.0-compatibility in its 2024 television lineup for the United States. This decision was not made lightly, b
159.
by drmpeg 3y ago
You'll like my IP over DVB-T2 test bed using GNU Radio. It uses the ULE protocol dvbnet driver that's built into Linux. Not shown on the diagram is that it also supports IPv6. https://www.w6rz.net/ofdm3.png
160.
by drmpeg 3y ago
No, there's very little loss from the atmosphere at 432 MHz. The 390 dB figure is a misunderstanding of how the path loss is calculated. The poster "wl" took the one way path loss (195 dB) and doubled it. But the moon is a hu
161.
by drmpeg 3y ago
It's not that high. You have to use the radar equation with the moon being a very lossy but huge target cross section. The path loss at 432 MHz and average moon distance of 384,400 km is 261.6 dB.
162.
by drmpeg 3y ago
I'm pretty good pals with my immediate neighbors, right, left and across the street and we talk whenever we see each other. My favorite neighbor Lois moved away after retiring. We used to call her the "CIA agent" because she
163.
by drmpeg 3y ago
I actually took the Captain Zilog self-study course (probably in 1981 or 1982). They mailed you the first installment and you answered the questions. Then you mailed back the answers to get graded and receive the next installment. I think t
164.
by drmpeg 3y ago
The beam width is 0.65° at x-band. If it's off pointed by 0.5°, the signal will be 7 dB lower (which in this case, is a lot).
165.
by drmpeg 3y ago
Probably a better example than WiFi would be the on-chip SDRAM controller. It's always somebody else's IP and there's a blob in the boot firmware that's just binary register settings. Like so: https://github.c
166.
by drmpeg 3y ago
The GNU Radio project dumped Swig and replaced it with pybind11 for the same reason. Just a nightmare when things go wrong.
167.
by drmpeg 3y ago
Back in 1983, when Ethernet was still fat coax and vampire taps, I was working at a military contractor in Silicon Valley. We had built an Ethernet bridge product that linked the DECnet LANs at DSCS (Defense Satellite Communications System)
168.
by drmpeg 3y ago
188 byte Transport Streams are allowed in ATSC 3.0. but it's a legacy mode. All ATSC 3.0 stations on the air use UDP over IP packets.
169.
by drmpeg 3y ago
https://www.fcc.gov/ecfs/search/search-filings And then put RM-11953 in the Proceeding(s) box.
170.
by drmpeg 3y ago
The CL4040 had two CL4020 chips in the package. It took four chips to encode 1/2 D1 resolution (352x480), so this was the smallest MPEG-2 encoder possible at the time (1995). The TMS320 chip was the audio encoder and was only capable o
171.
by drmpeg 3y ago
I found another item that I hung onto. A CD with the i960 tools including gcc (looks like it's gcc 2.7.2). Also has a bunch of manuals in PDFs. https://www.w6rz.net/IQ80960RXK5_2.iso 105,078,784 bytes.
172.
by drmpeg 3y ago
I worked on a bunch of MPEG-2 encoder and decoder designs using the i960CF and i960RP when I was at Optivision. Here's a photo of an MPEG-2 encoder (found on E-bay) that used the i960CF and a PCI interface chip designed specifically fo
173.
by drmpeg 3y ago
Depends on the signal. There is lots of complexity in a 4G LTE or 5G signal. Take a look at the waterfall of this 4G base station. https://www.w6rz.net/attlte.png
174.
by drmpeg 3y ago
Writing a T-STD compliant TS multiplexer is not trivial. When I was at LSI Logic, I spent many hours perfecting the TS multiplexer used on the MPEG-2 encoder in the Motorola DCT-6412 P3 STB. Here's a short clip that's T-STD compli
175.
by drmpeg 3y ago
You would have loved the old ATI/AMD demodulator evaluation board that I have. Does both ATSC 1.0 and QAM. TS output is DVB-ASI (which requires a pretty expensive DVB-ASI to USB converter). https://www.w6rz.net/DCP_1205
176.
by drmpeg 3y ago
Fun fact. DOCSIS 1.0 through 3.0 cable Internet uses MPEG-2 Transport Streams to deliver the IP packets. It has to, because the QAM specification (ANSI/SCTE 07) is built around 188 byte TS packets.
177.
by drmpeg 3y ago
Yes, Intel even had their own bus for this called Multibus. The processor lock signal was connected to the Multibus so that a bus master could lock another boards shared memory for an atomic access.
178.
by drmpeg 3y ago
Apples and oranges. Those numbers are for a 50 Hz bandwidth mode. LoRa is 125 kHz, so it has a 34 dB disadvantage. Also, those numbers require the HB9Q 50 foot dish to be at the other end.
179.
by drmpeg 3y ago
Their advisor is Al Katz, K2UYH whose been doing EME for as long as I can remember.
180.
by drmpeg 3y ago
For RISC-V, there's the PolarFire Icicle from Microchip. Fully supported in mainline Linux. https://www.crowdsupply.com/microchip/polarfire-soc-icicle-k... Not cheap at $599.

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