DCR-974 “Digiceiver”

digiceiver

NOTE:  Due to the delivery of the Learfield XDS Satellite System, the Digiceiver satellite platform will be terminated as of January 27th, 2017.  All Learfield programming will be delivered via X-Digital (XDS).

Receiver Installation

Important: Make all satellite RF and audio connections prior to applying AC power to the Digiceiver.

Satellite

Learfield programming via the Digiceiver is delivered through AMC-8 (formerly known as Satcom C5). AMC-8 is located at 139° West Longitude.  If you are installing a new satellite dish more information may be obtained from our Dish Installation Guide or the Azimuth/Elevation Chart.

Software Version

To ensure proper operation your Digiceiver must contain the latest version of the operating software. Learfield utilizes two Digiceiver models. Most stations will have the DCR-974, while some stations will be using the DCR-974RT. At power up your Digiceiver LCD display will read either: DCR974 – VERSION x.xx or DCR974RT – VERSION x.xx. The latest software for the DCR-974 is 2.23B, while the DCR-974RT should be using 3.07. If your receiver contains a version other than this please contact Learfield Engineering at 573-893-1955 to arrange for a software upgrade.

LNB Power

Your Digiceiver is shipped with the LNB power turned off. If your LNB receives power from another source leave the Digiceiver LNB power turned off

To turn the LNB power on:

  1. At power up your Digiceiver LCD display will read: DCR974 – VERSION x.x (Some receivers will have a model number of DCR974RT, the instructions are the same for both)
  2. Press “CURSOR (right)” until the display reads ‘DEMOD’, Press “ENTER”
  3. Press “PAGE (down)” until the display reads ‘LOCAL CONTROL’, Press “ENTER”
  4. Press “PAGE (down)” until the display reads ‘LNB POWER’,
  5. Press “VALUE (down)”, Press “ENTER”
Click image to enlarge

Click image to enlarge

Signal Strength

At installation, verification of your RF input signal strength is recommended. To check the signal strength

  1. At power up your Digiceiver LCD display will read: DCR974 VERSION x.xx
  2. Press “CURSOR (right)” until the display reads ‘DEMOD’, Press “ENTER”
  3. Press “PAGE (down)” until the display reads ‘SIGNAL STRENGTH’
  4. Signal strength above 10 is acceptable. A reading below 10 indicates excessive signal loss in your downlink setup.

The second part of checking signal quality is to check the SYMBOL ERROR RATE. To view this reading:

  1. From the SIGNAL STRENGTH reading Press “Page (down)” once.
  2. A well aligned dish will see a SYMBOL ERROR RATE of 0.0. (alternately the display may show only dashed lines instead of 0.0)

The display shows the error rate of the satellite channel before error correction. For example, if the display shows 1.0 E-5, then the Digiceiver is detecting one error in every 100,000 recevied bits (1.0 x 10-5). The result is a very accurate estimate of the link error rate. This is NOT the error rate the user will experience. The FEC decoder reduces this error rate by many orders of magnitude.

How much Signal Strength do you need?

The DCR-974 Digiceiver is equipped to provide the user with a highly accurate measurement of the amount of signal reaching the receiver. Signal strength is displayed as estimated Eb/No. The estimate is derived from the demodulator chip and is a valuable aid to antenna peaking and signal level monitoring. A signal strength measurement of less than 10.0 indicates less than adequate levels of RF are reaching the receiver. The lower the level of signal reaching the receiver the more susceptible it becomes to experiencing noise and/or errors within the received signal. (Obviously once the signal drops too low the receiver will unlock providing no audio output.) Conversely, the higher the signal level the less likely it becomes that errors and/or noise will be experienced. Low signal levels can be the result of many different problems within a stations downlink installation. The most common, and usually easiest to correct, is mis-alignment of the satellite dish. A mis-aligned dish will receive less RF from the satellite, thus giving a lower reading. For tips on how to properly align your satellite dish refer to the Dish Installation Guide. The next factor in signal strength is the quality and type of coaxial cable used in the installation. Most common with L-band installations is RG-6. At 1450MHz RG-6 cable will lose about 8.7 dB of signal per 100 feet. Where RG-8 cable will lose only 4.5 dB per 100 feet. Other conditions can provide temporary reduction of RF signal, including sun transit periods and severe weather conditions.

Audio Connections

The audio outputs for your Learfield networks are available via the DB-9 Decoder outputs on the receiver backplane. Refer to the ‘RECEIVER SETUP’ sheet included with your Digiceiver to find the decoder output assignments for your network(s). Decoder outputs are configured and authorized for your station prior to shipping.

Balanced Audio Pinouts for DB-9 Decoder Outputs

  • Left (+) pin 4, Left (-) pin 9
  • Right (+) pin 2, Right (-) pin 7
  • Ground pin 1 and/or 3

Data Port Connections

If you subscribe to Learfield delivered data products, such as state news or weather information, this service is provided via PORT 1 on the rear panel of the DCR-974 Digiceiver. The data port is enabled and configured for your station prior to shipping.

  • Data Port 1 Pinouts for DB-9 Male
  • Data High pin 2: Xon-Xoff pin 3
  • Data Ground pin 5

The pin inputs to your existing data capture service (WireReady or printer) will depend on the input connector type. Use the table below to select your input connector and use the pins indicated.

Printer Only

  • Xon – Xoff pin 2
  • Data High pin 3
  • Data Ground pin 7

Computer DB-9

  • DB-9 Data High pin 2
  • Data Ground pin 5

DB-25

  • DB-25 Data High Pin 3
  • Data Ground 7.

Audio Decoder Channel Assignments

Digiceiver audio channel assignments are grouped in pairs. The following is a list of channel assignments for networks uplinked by Learfield with the Digiceiver system. Not all networks listed may be available with your receiver.

Note: Left and Right channels are always paired together and may not be switched independently.

 

Click image to enlarge

DCR-974 Settings

Proper operation of the DCR-974 can only occur if all menu choices are programmed to valid settings. Upon shipping, your DCR-974 has been pre-programmed and tested to assure proper operation. In the event you need to reset your receiver settings the following chart provides valid options for each parameter.

 

Trouble Shooting

Symptom A: Power Indicator Off

  • Check AC outlet to make certain that the unit is connected to a live circuit
  • Check chassis fuse. If blown, replace with correct fuse. If fuse blows again other problems may be present.
  • In rare instances, the POWER indicator may be faulty but the receiver will function normally.

Symptom B: LNB Indicator On

  • If the LNB is NOT powered by the receiver, make certain that LNB power is disabled via the front-panel control. The LNB indicator will light if the power output from the receiver is not disabled when a separate LNB power supply is installed. (see Section 2.3 of the Digiceiver manual)
  • Check the LNB fuse. If the the fuse is blown, the IFL or LNB may be shorted. Replace fuse with a 5x20mm fast-blow, 0.5 Amp maximum spare. If the replacement blows, disconnect the LNB and check the cable for a short. Total current draw should also be checked. DO NOT exceed 0.5 Amp draw on the LNB power circuit. If the LNB fuse is normal check to make certain the LNB is securely connected to the cable.

Symptom C: Fault Indicator On

  • Turn off AC circuit at the rear panel. Wait a few moments, then reapply power to reboot the control circuits
  • If problem cannot be otherwise solved a replacement unit may be needed.

Symptom D: Demod Indicator Off

  • This symptom is caused by either loss of demodulator lock on a received signal, or by the input signal not being present.
  • If LNB indicator is also lighted, perform checks in B.
  • If Fault indicator is also lighted, perform checks in C.
  • Check to make sure the receiver is set to the proper mode, bit rate, frequency, sweep width, and carrier ID.

Symptom E: Carrier ID Indicator Off

  • If the carrier ID value is set incorrectly, the receiver will lock only momentarily (the DEMOD indicator will flash on), and then continue to sweep. Recheck carrier ID setting.

Symptom F: DN LOAD Indicator On

  • If the DN LOAD indicator is flashing then the receiver is being downloaded with new software. Wait a few minutes for normal operation to resume.
  • If the DN LOAD indicator is on, the operating code of the receiver has become corrupted. Try recycling power and allow the receiver to re-boot. If re-booting does not correct the problem, contact Learfield for a new software download.

Symptom G: Excessive Errors or Noise

  • Make certain receiver is not tuned to an improper frequency.
  • Make certain the selected sweep width matches the characteristics of the LNB being used.
  • Check the signal strength display. A low reading will usually be accompanied by noise and errors on the receiver.

Symptom H: Other problems

  • If panel display is blank or garbled, turn off AC power at the rear panel. Wait a few moments, then re-apply power. If the problem continues, replace the receiver.