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Discussion Starter · #1 · (Edited)
(Note: this was originally posted at the Stellar Labs ATSC HD Modulator thread, which the Channel Master modulator appeared to be a close copy of. That turned out to be wrong so I'm creating a new thread for discussion of the Channel Master modulator.)

Channel Master recently announced a new ATSC modulator, currently selling at $299 ("regular" price $349, but they don't say how long the $299 price will last), that looks a lot like the Stellar Labs modulator. Edit: Photos can be deceiving! I have one now, and while the CM modulator does look like the SL one, the box is considerably smaller. In fact it's only slightly larger than the Souka modulator (the Thor Petit clone).

Edit: My pictures went away but @videobruce has posted pictures and much more info at post 7 (thanks!)

Externally, the main difference is the removal of the HDMI pass-through port and replacement with an RCA jack labeled "Caption." There's also a new Ethernet jack. But according to CM's Web page, this new mod sports a few features sorely lacking from the SL mod:
Agile Channel Selection (Channels 2-99) This is a typo; the actual RF output range is 2-69 as you'd expectSupports Creation of Sub-ChannelsConfigurable PSIP data (Channel Name, Major Channel #, Minor Channel #)Closed Caption SupportLAN Management via Ethernet Port

Video Output Format480i/p, 720p, 1080i/pCaption InputComposite VideoRF Output Frequency57-861MHzOutput Level90 dBuV (Minimum)Channel Level Adjustment0dB - 30 dB (Typical)MER35 dB (Typical)Video CompressionMPEG2AudioMPEG-1 Layer 2, AAC-LC, AC3

(I'm not sure where they got that top RF output frequency of 861 MHz. RF 69 is 800-806 MHz, and would presumably have been listed as its center frequency of 803 MHz. 861 MHz is the center frequency of cable RF channel 135, but this modulator doesn't do cable.)

So, you're not stuck with the (illegal) "channel 0-0" produced by the SL modulator, you can change the channel name (not fixed at "Stellar"), it can do 1080i(/p? which must refer to the RF output since there's no HDMI pass-through), it can output at VHF frequencies down to RF 2 (54-60 MHz), and it supports the standard "Dolby Digital" audio codec. These improvements should help with the compatibility issues folks had with the SL mod and put it more in line with the (apparently no longer available) Souka modulator.

One interesting feature of this modulator is that it will encode 1080p from, e.g, my Roku. (I was surprised to learn that ATSC even supports that, but according to Wikipedia, at lower frame rates it does, and it seems to work on the devices I've tried so far.) But don't get too excited: it's 1080p30, so there's minimal improvement over the 1080i we're used to with ATSC. You're still getting 1080 lines every 1/30th of a second; those lines are just arriving in a different sequence. (1080p60 is what folks really want for improved video, but that is beyond ATSC 1.0's abilities.) However, if you run into a TV or tuner that chokes on 1080p, there is an option to convert the input to 1080i that you can enable.

As with other ATSC modulators I've tried, it's output seems clean: there's no noticeable bleeding of RF into channels above or below the RF channel you set. However its output signal strength is noticeably weaker than that of the SL and Souka modulators, so if you mix the Souka and CM modulators and put them on adjacent RF channels, you may need to set the Souka modulator to attenuate its output somewhat. (Or just amplify the CM modulator's RF output with a decent distribution amp before feeding it to the Souka modulator.)
 

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Do you happen to have any way of capturing a short test .ts stream file of the CM’s output? I’d be curious to know if it produces a valid header, etc. with its stream. I know the Stellar Labs and PVI Pixel modulators I tested in the past produced junk file properties that created issues with some software and capture devices.
 

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Discussion Starter · #3 ·
I'm not sure. Most DVRs only capture the A/V packets, but I might be able to capture the full stream with my iView CyberBox; I'll give it a try.

In the meantime, I analyzed a few minutes of its output with TSReader Lite. I attached the HTML analysis file below (remove the .txt extension then open it in your Web browser). Lots of "continuity errors," whatever that means.

The PID numbers are a bit unusual; I was experimenting but once I had everything working I didn't want to touch anything!
 

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Discussion Starter · #4 ·
One thing I noticed is that despite having a date/time setting in the menu, the CM modulator doesn't send a System Time Table. The Souka modulator does send a STT, and in fact can reference an NTP server to keep its date/time correct (after power failures and the like).

On the CM modulator, I'm not sure what the point of entering the date/time is....
 

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I'm not sure. Most DVRs only capture the A/V packets, but I might be able to capture the full stream with my iView CyberBox; I'll give it a try.

In the meantime, I analyzed a few minutes of its output with TSReader Lite. I attached the HTML analysis file below (remove the .txt extension then open it in your Web browser). Lots of "continuity errors," whatever that means.

The PID numbers are a bit unusual; I was experimenting but once I had everything working I didn't want to touch anything!
I would appreciate it. Pretty much any ATSC DVR recording should answer my question. Even 20-30 seconds should be plenty. In the previous tests I did with the Stellar Labs & Pixel Modulators I was trying to use them to feed a signal into my TiVo. My goal was to "record" some content that is only available on streaming providers on the TiVo and then save those recordings to Blu-Ray. Unfortunately the streams were such a mess it caused all the editing software I usually use to crash when trying to work with them. I just wondered if this particular modulator is any better.
 

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I would appreciate it. Pretty much any ATSC DVR recording should answer my question. Even 20-30 seconds should be plenty. In the previous tests I did with the Stellar Labs & Pixel Modulators I was trying to use them to feed a signal into my TiVo. My goal was to "record" some content that is only available on streaming providers on the TiVo and then save those recordings to Blu-Ray. Unfortunately the streams were such a mess it caused all the editing software I usually use to crash when trying to work with them. I just wondered if this particular modulator is any better.
I was about to pull the trigger on a purchase until I read your post. That was my thought too. Buy one to feed my Bolt to avoid the commercials. What about a 30 min delayed viewing, using the tivo to skip thru the adds of a live 60 min program? Any issues? Picture quality? And does it pass 5.1 Audio?

What kinds of editing software were you using? VideoReDo one of them?
 

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From Channel Master;
Rear panel labeled ports and Web interface pages (after a IP address is established)

CM CM1050 rear panel labeled.png
_CM CM1050 Sys Info-combined.jpg
_CM CM1050 A&V Settings combined.jpg
CM CM1050 Network Device Mgnt.png
CM CM1050 Operating Instructions 1.png
CM CM1050 Operating Instructions 2.png
 
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From me, screen shots of initial tests and observations; most should be self explaining.
The three SA shots were at -2, -10 & -30db attenuation levels from the 38dBmV max output.
The last 3 were taken off a 720p (768 actual) smaller display, not a true 1080p. (Camera white balance is off, hence the 'bluish' tint)
"Test __" is what I renamed the channel name to.
That 'blue screen' is their 'fill' image when there isn't a HDMI source connected.

Device display screens (combined).jpg
CM1050 signal level range.jpg
Haystack at minus 2db out.png
Haystack at minus 10db out.png
Haystack at minus 30db w table.png
Test patterns of RF28 output.jpg
 

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The biggest complaint about this is the display. Instead of showing a completely useless ATSC 8VSB which tells one nothing and that time counter, how long it's been on (more useless), why they didn't have the basics;
Channel, Frequency, Power output.
is beyond me. The the navigation within the menu is a joke. One keeps getting edited out of the menu when you press the left navigation button depending on where you are. The simple task (or should be) of changing levels or channels is a PIA!
Admittely, that cam be done using the web interface, but for simple talsk, why not use the internal menu?


I received a replay to questions about the display on the device itself. Specifically, those 3 indicators in the upper left. One should be used for presence of a Ethernet connection.
I don't see the need for a 'timer' clock taking up space (in the upper right corner), better used for the output level among other more worthwhile details.
CM1050 display notes.png


CM1050 interior labeled.png


Click to open full image;
CM1050 PCB full.JPG

Components;
ARM® Cortex®-M4-based STM32F4 MCU Microprossor;

ARM STM32F407 & MXIC MX 25L3206E.JPG


Macronix (MXIC) 25L3206E 32MBit 4Mb SPI flash

Semiconn EP 9351 HDMI 1.3 receiver;

Analog Devices ADV 7182A 10-Bit, SDTV Video Decoder;

Semiconn EPF021A Generic 8 bit MCU w/ 64KB eFlash;

FUDAN MICRO FM24C16D 2 wire serial EEPROM;
www.fmsh.com/nvm/FM24C16D_ds_eng.pdf

Notes on missing components;
IC3 & IC33; unable to remove heat sinks
IC22; I missed :(

A interesting circuit. I tried to find out what those 2 IC's are, but both numbers turned up nothing. Anyone else have any idea??;
RF section.jpg
 

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Tried one of these out today and it didn't go so well. Signal dropped out 3 times in about 5 minutes and there was some latency when using the menus on my Dish receiver. I went back to my HDMI over coax setup.
 

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Discussion Starter · #11 ·
Latency is an issue with most ATSC modulators. It has to do with how MPEG-2 video compression works. There's a "Video Profile" setting on this one that might help: try reducing the latency setting (obviously). If that doesn't help, try reducing the GOP setting a bit.

As for the dropouts, I noticed that the output of this modulator, even at zero attenuation, is somewhat weaker than the other two I use (the Stellar Labs and Souka ATSC modulators). I had a similar problem with an analog (NTSC) modulator and ended up putting a distribution amp in the chain to fix the issue:

NTSC mod ---> CM ATSC mod ---> CM-3410 RF amp ---> SL ATSC mod ---> Souka ATSC mod ---> super home node in attic
 

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Additional processing by the modulator introduces delays.
 

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Discussion Starter · #13 ·
Interesting that the modulator's circuit board provides space for an HDMI pass-through output jack, as seen on other ATSC modulators. I wonder why CM chose to leave it off of this model?

Will also be interesting to see if anyone else turns up selling a clone of this modulator. Except for antennas, CM almost never sells equipment of their own design.
 

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Cost or specifics from whomever the actual manufacture is (they didn't want to allow that feature to this 'seller'). AKA marketing. ;)

The CM name is just that, a name the Andrew Corp bought after CM went into Chapter 11 in 2003, closing their plant in a non-union N Carolina (16,000 employees) which use to be in New York. :mad:
Based in Arizona, their employment now is a whopping 17 employees;

Footnote; The CM's DVR's (in conjunction with Echostar) went away first thanks to Rovi and now thanks to Xperi with their 10,000 patents meaning thye own the DVR market, aka TiVo;
www.theverge.com/2019/12/19/21029945/tivo-xperi-merger-dvr-rovi-deal-patent-licensing
 

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Discussion Starter · #15 ·
Yeah and 9,990 of them are ridiculous "inventions" that should never have been granted a patent! Like "inventing" the grid-style guide! (Resulting in absurdities like SiliconDust's "slice guide" for their DVR service.)

This is off-topic, but those interested in keeping their CM (Echostar) DVR+ alive may be interested in PiGS: The Channel Master DVR+ EP Guide Server Replacement. Replaces the free but poor-quality guide provided by Rovi/TiVo with a cheap ($25/yr) but excellent-quality Schedules Direct guide. The PiGS/DVR+ combo got an exemption from SD's normal no-commercial-product rule due to the DVR+ being a discontinued product that's no longer marketed or sold new, and everything else being free (except the PC, which you already have).
 

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I’d still love to see a short test recording .ts stream from one of these if someone could capture one. I’d like to see how well it specs vs the other boxes
 

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This is interesting to see cheap ATSC 1.0 modulator and I wonder that can be put to use on 420 to 430 MHz ranges for ham radio TV with proper filters when putting through Amplifier? "FCC licenses required"
 

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Discussion Starter · #18 ·
This particular modulator is probably unsuitable for ATV because it's preprogrammed for just the specific frequencies used by OTA channels 2-69. The Souka modulator I own, however, can be set to cable channels 57-61, which correspond to the 70 cm ham band. Unfortunately the Souka modulator appears to be unavailable any longer, but the (unfortunately more expensive; $465 IIRC) Thor Petit should do the job also.

Another option: in the analog days cable TV companies often used frequency shifting devices to move TV channels from their OTA frequency to a cable channel frequency more convenient for their system. These devices are stable enough for ATSC digital modulation, so if you could find a used one with an output frequency on cable channel 57-61, you could set the CM modulator to the device's input frequency to create a broadcast-ready ATV signal.

I don't know if FCC regulations allow ATSC modulation to be used on ATV, but it appears technically feasible at least.
 

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The output channels are only US TV channels.

Using a CATV channel map, is the output QAM or ATSC??
 

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Discussion Starter · #20 ·
With the Souka modulator, it looks like switching to the cable map also switches the modulation to QAM. (You get the choice of QAM64 or QAM256.) I don't know if the Thor Petit lets you output ATSC on cable frequencies, but using an ATSC modulator (like the CM) with a frequency shifter would get you there.

But then you'd have to ask, what would you receive the broadcast on? Most TV tuners are going to look for QAM signals on those frequencies. So if you're trying to broadcast digital ATV (again assuming this is legal) you're probably better off using QAM modulation anyway.
 
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