Inside of the Motorola DCT STB's there is a diagnostics screen that you can use to troubleshoot problems with your box. Mostly these screens help with problem you maybe having with your digital channels (ch 100 and up). These problems can be video dropouts, tiling, micro/macro blocking, ect. Lets start with how to enter into the Diagnostics screen:
Turn the DCT OFF > press SELECT (within 2 sec)
Using your ARROW KEYS to move up and down the list and press the SELECT button to see more information. Pressing SELECT again will then take you back to the main menu.
This will only go over the screens you may need for troubleshooting, as some of the screens do not offer any pertinent information.
First Screen of importance is d03
OOB - Out Of Band
This is a tuner inside of the DCT that interprets signals sent from the local Cable provider for the On-Screen Guide & Menus, as well as signals for activation. If your box is working then the info here doesn't really much matter. I'll go over the SNR & AGC below.
d04 In Band Status - The information on this screen is related to the last channel that you were tuned to before entering the diagnostics screen. In order to see information for the other channels you need to exit the diagnostics, turn the DCT back on then tune to the channel you want to check, then repeat the process to enter back into the diagnostics.
.............................This is an HDTV channel.........................................................................This is a regular Digital Channel
Mode - is the Modulation scheme being used for this particular channel
256 (common for HDTV) data rate is about 38.8 MB/sec
64 (regular digital ch, high speed internet, ect.) data rate 26.9 MB/sec
SNR - Signal to Noise Ratio - this is the amount of separation between the signal level & the amount of noise under that particular carrier. The higher the here number the better.
AGC - Automatic Gain Control - This represents the amount of adjustment that the box is making to the signal in order to make the level for the data stay within the "sweet spot". The higher the percentage the harder the box is working to adjust the signal, usually meaning there MAY be some issues with the signal coming into the STB.
These numbers don't really mean anything unless you are having problems with your digital channels. If you are, then the real information you need in order to troubleshoot is below.
5 Second Error Counts
This section is actually the most important of the bunch. Even though the DCT Diagnostics does not have the ability to show the actual signal level of a given carrier (channel), that really doesn't much matter when it come to digital signals. What counts is the quality, not the quantity of the signal.
Correctable Errors - this is corrupt digital data that the STB has the ability to "piece" together before its sent to the D/A (digital to analog) convertor. This function samples the signal for 5 seconds and displays the number of bit errors in the signal. Numbers in this section WILL NOT cause any visible problems with the picture on your digital channels. But numbers here could eventually cause uncorrectable errors below.
Uncorrectable Errors - This is corrupt data that the STB CANNOT "piece" back together. This means that the data is either of too low of quality or quantity (level) in order for the STB to know what it is supposed to be. This will result in issues with your digital channels, micro/macro blocking, tiling, and possibly complete video & audio dropouts.
You can then take your STB to various locations in your cable drop system, as long as you have a small TV to hook the box up, in order to view these numbers.
It isn't unrealistic to want or see 000's in these locations. There will be occasional dropouts, but if you have consistent problems then you should check these numbers and use them to troubleshoot, these problems.
d06 Current Channel Status
The top line on this screen shows what type of signal is on this channel and whether or not its encrypted.
ENC - Encrypted CLR - In the Clear or unencrypted
This screen tells you what frequency the channel you are tuned to, is on. If you are having problems with multiple channels in you digital line-up you may find that they are all on the same frequency, meaning that they are all subject to the same interference.
Cable companies can put as many as 8-10 SDTV channels (3-4 MB/sec) onto one 6 MHz carrier. This frequency just represents the center of that 6 MHz carrier.
This screen also tells you weather or not it is working or authorized to work.
d07 - Upstream Modem
This gives you some information about the signal being sent back to the cable company, for services like IPPV, VOD & eventually ITV. This screen is telling you that the frequency in which this signal is sent back is centered at about 8 MHz. And the amount of signal that the modem has to generate to get its signal back to the Cable Co. Headend is 53 dBMv. Maximum for this is 60 dBMv.
If your VOD is not working or while trying to have the box activated by your local Cable co and they are saying that it is not responding, then is likely that the return signal from your DCT is being blocked or attenuated too much by:
-The input cable is looped through a surge protector
-The input cable is looped through
the TV's
Ant A/Converter Out/Ant B RF
jacks on the back of your TV.
-The input cable is looped through the VCR before the STB
-The input cable is running through equipment (amplifiers, splitters, ect.) that
is not capable of passing return, and/or doesn’t meet 5 MHz-1000 MHz specs
-High pass Filter on cable line designed to block out low band noise
-Poorly made fittings, corrosion and/or water in fittings, bad/old cable lines
-Too many splitters in-line with the offending STB.
If you have a cable modem or another digital box that it is working fine then you can rule out an issue with a problem out on the cable system.
d09 - Interactive Status
This gives you more information about the RF modem inside the DCT that send & receives information. The way you see it here is something very similar to what you should see when everything is functioning properly. Most notably you should have an IP address. This validates that the DCT and the Local Cable Co. network are communicating.
I hope this helps you with any issues you encounter when troubleshooting an issue with your digital channels on your Motorola DCT series STB.
