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FAQ Questions and Answers
What is the difference between Push-Pull and Power-doubling?
Push-Pull amplifiers have a little lower distortion specification than Power Doubling. If you have more than two amplifiers in series in the system (not total amps in the system, but total number of amps the signal passes through to get to the furthest outlet) it is recommended to use the Power Doubling amplifiers, to minimize overall distortion. You can typically go up to 3 or 4 amps in series with power doubling, and still maintain FCC spec on distortion.
What is the difference between an SRT and DGT directional tap?
The SRT series has been around longer. The DGT series was created in the past few years, for the Digital signals. The DGT series has undergone additional testing to become “Digital Certified” – meaning it has passed additional testing to be suitable for digital signals.
The SRT series has been installed in tens, if not hundreds, of thousands of digital systems, without issue. The biggest difference is that the SRT doesn’t have that additional testing certification. Both series will work equally well, but if you need a component that is digitally certified, go with the DGT.
I understand that to calculate the input level of an amp, you take the high-rated output minus the gain to get the input level, but is that a minimum level or a maximum level? In other words, if I have a BIDA 1000-43P, which has an output of 40dB and a gain of 43dB, that would make the input level -3dB. Does that mean -3 at 1000MHz or flat and is that a maximum level? What happens to my output if my input is, say, +3dB?
Output level minus gain gives you minimum input level needed to get the rated output.
If your minimum is -3dBmV, and you hit it with +3dBmV, you are getting better noise, but a little worse distortion through the amp. If this is the only amp in the system, not a worry. If this is 3 or 4 amps into the system, it may cause too much distortion.
Is there a spec sheet available on the BIDA-CE series cable equalizers? I assume that these equalizers attenuate the lower frequencies more than the higher frequencies given the fact that cable loss is greater the higher the frequency but I would like to know what the attenuation value is at a given frequency. Do you have a formula or chart that shows this?
There is no specific marketing spec sheet for the BIDA-CE equalizers. But I can tell you that they are pretty linear. So if you are coming in to an amplifier at 26/20 dBmV, and use a 6 dB CE, there will roughly 20/20 (plus an additional 1 dB insertion loss across the board), making the final output of the CE 19/19 dBmV.
To figure out a level in the middle, you’d have to break down the frequencies. 50 to 860 MHz is a total of 810 MHz, middle of that is 405 MHz. So at 455 MHz is the middle of the range, in a 6 dB CE, there is 3 dB loss. Spit that again, and at 657.5 MHz, there is only 1.5 dB loss.
Why can’t I get my TV’s to lock to the QAM output for my encoder?
Verify the following settings under the “QAM” tab:
1. Output Control is “ON”.
2. CW Control is not checked.
3. Output Channel /Frequency is selected.
4. Final Output Level is set appropriately based on system requirements.
Verify the following setting under the “TS Config” tab:
Multiplexed MPTS Output Configuration > TS Bitrate – “QAM Modulator” must be selected.
I cannot see the QAM output even though I have turned the “Output Control” ON on the “Main > QAM” screen and have selected the QAM RF channel number on the “Main > Output” screen.
Ensure “QAM Modulator” option has been selected under “TS Bitrate” on the “Main > QAM” screen
Some of my TV sets, set-top boxes or other digital demodulators are not picking up the QAM output of the HDE-4S-QAM (or HDE-2H/2S-QAM), yet the majority of devices on my system are working just fine.
Here are a few of the units we found that will not work with standard QAM; Extron ATV 200 HD tuner, Contemporary Research 232-ATSC (the newer 232-ATSC+ works fine), some Sansui TV sets, & Digital stream DCS1000 Digital Cable STB.
Some devices will only recognize inverted QAM signals, check the software version of the DDQ module. IF the version is 1.7 then the QAM out is normal, if version 5.7 then the QAM is inverted. Contact Blonder Tongue technical support for additional help and for the upgrade files.
I have SDI inputs without embedded Audio. Will your unit allow me to add audio to my existing SDI input?
Yes, both the HDE-2H/2S-QAM and HDE-4S-QAM allows the user to add audio from one of the other inputs (analog audio, digital audio or audio from the HDMI input). The unit allows the mixing of any of the audio and video inputs.
Is the HDE-2H/2S-QAM or the HDE-4S-QAM unit capable of adding a second audio (example if incoming source is HD-SDI with embedded audio), can another audio be added through the component audio connections or other audio input?
No, the unit cannot add two different audio sources together. It can take the audio from any of its input sources and embed them with any of its video inputs, but only one audio source can be embedded at a time.
The unit can pass multiple audio channels, if they are already embedded on the SDI input stream.
If there is no input connected or to your encoder, what can I expect on the output QAM?
The units will internally generate color bars (720p @ 60fps).
When using a 1080p input source on the HDE-CHV-QAM, why do I have picture issues?
The unit is not designed to work with a 1080p input source. The inputs formats supported are: 480i, 720p, & 1080i.
When I use the IP Reset button on the HDE-CHV-QAM, why doesn’t the encoder go back to the default setting?
To reset the IP address to the default address, the unit must be powered up and the reset button held in for at least 10 seconds. This helps prevent accidental resets from momentary button taps.
Can I set the IP output bitrate to lower values on the AQT8-QAM/IP? For example, instead of sending a stream to 19 Mbps bty default, then use 2 Mbps?
19 Mbps is the lowest you can set, but if you disable stuffing in the IP tab, it will not fill to 19 Mbps; it will only pass the actual data, reducing the overall bitrate.
The front lights on my new AQT8-QAM/IP are flashing green. From the user manual, it's because the EAS is enabled. Can we stop the flashing?
The input lights will also flash if the QAM out is turned off or put in CW mode for that channel. If you are using IP output only, and have turned off the QAM output, the lights will flash.
How do you change the input to SDI with embedded audio?
Upon logging into the unit, go to the video tab to chance video parameters, and audio tab for audio parameters. Top line item for each input source, which is a drop-down list. Select the inputs you want and click “SAVE” button at the bottom of each page before moving on.
How do I choose the right value and what should be the normal in terms of taps value?
The attached white paper will shed some light on this for you.
When would you use push-pull amplifier vs a power doubling amp? What is the major difference?
|The power doubling style has better distortion specs, and would be used if you need 3 amplifiers in series. 1 or 2 amplifers in series can be used with the push-pull style. More than 2 in series will generate too much distortion for good pictures.|
If you have 3 amps in a series, can the last amp in the series be push-pull or should they all be power doubling?
|Distortion is cumulative, so if running 3 amps in series, all should be power doubling to keep the distortions low enough to maintain FCC compliance. If any of the 3 are push-pull, unless you lwer the rated output of the amp, it will cause undue distortions and affect the picture.|
Is there a setting on the HDE-CHV-QAM to reduce latency, or an alternate encoder model that has lower latency that we could use?
|The HDE-CHV-QAM does not offer a low latency option. The only unit we have that does offer low latency is the HDE-4S-PRO, but its inputs are HD-SDI.|
What is the difference between the SRT taps and the DGT taps?
|The SRT series has been around longer, and is proven to work fine with analog and digital signals. The DGT series has undergone additioanl testing to be “Digital certified;” it also will handle digital and analog signals no problem. The SRT series has more options available.|
Will the AP-60-860A process 8VSB input to 8VSB output?
No, the AP-60-860A has three operating modes.
i. Analog input to Analog Output
ii. QAM input to QAM Output
iii. QAM/8VSB input to Analog Output
Will the MDDM pass all programs from the off-air channel?
No, the MDDM will pass only ONE program from the selected RF channel, not the entire channel.
Is the MDDM unit’s software field upgradable?
Yes, this unit is field upgradeable, through the Mini-USB port.
How do I get my MDDM-860 to output both audio and video when feeding it from a Drake DSE24 with a HDMI 1080i input as I only get audio? I’ve substituted other digital demodulators and TV’s which work fine.
Check that the video profile is set to MP@HL on the Drake DSE24. Some tuners will not lock in if the profile is not correct. Profile settings for the DSE24 should be MP@ML for 480 @30fps and MP@HL for 720 @ 60fps or 1080 @ 30fps.
I’m having an issue with the QTM-HD / QTM-HD-NPU - it cannot lock to transponders of ECHOSTAR 8 @ 77º W. For firmware versions 3.6 (most likely shipped after 8/2007).
Firmware must be upgraded to version 3.7 in order to lock to these transponders. After upgrading to V 3.7, QTM will lock in “Manual” as well as “Auto” modes.
Is the 5800/5900 series of BIDA amplifiers set up for return path capabilities out of the box?
The 5800/5900 series BIDA is set for PASSIVE return capability out of the box. To activate the return amplifier you must open the unit and move jumpers around to enable the return amplifier stage.
Can I use FC/UPC connectors with the FIBT/FIBR in my system?
No, it is strongly recommended to use APC (angle polished connectors) throughout the system. Anywhere there is a flat connection in the fiber plant, reflections can occur, causing problems with the signal. Worst-case scenario is where the flat connector is near the transmitter, and it could reflect enough signal back into the transmitter as to cause damage.
Do I have to maintain my channels below channel 110 while using a FIBT or a FIBR?
These units are rated to 860 MHz, so you could run up to channel 135. If these units see more than 110 channels, you will need to lower the total input level into the unit, so the composite power does not exceed operating input.
Will the CEF (Channel Elimination Filter) work to eliminate a digital channel?
NO. The CEF was designed for analog channels, and we do not make it for digital currently.
I’m looking for the frequency information on digital channels. Isn’t analog dead? Why do you have analog information?
RFreq™ lists channel band edges, center frequency and legacy analog visual and carrier frequencies. Typically when referring to digital TV broadcasts in 8VSB or digital CATV QAM channels, the center frequencies are used. This app is for frequency referencing only, and requires the user to know what the source is. The digital transition (ie. the death of analog) primarily refers to when full power TV stations moved to digital broadcasts in 2009, or the fact that large CATV plants are moving toward all digital. However, as things are still changing, and for many niche/legacy applications where analog is still being used (like low power and translator broadcasts; businesses and schools CATV …), it is helpful to technical personnel to have easy access to all of the frequency information (which is why we developed RFreq™). Please see Apps By Blonder Tongue for more information.