FAQs

I have connected the fiber, but the receiver module still has a red LED on?

It is very easy for a fiber-end to become contaminated with dirt. All ViaLite equipment is supplied with a cleaning kit. It is recommended that a fiber-end is cleaned before inserting into the connector. When using FC/APC connectors, please note that these have a single slot ‘key’ position that must be mated first before the thread is tightened.

What type of optical connectors can I use with ViaLite RF over fiber systems?

Optical connectors are critical to the performance of a link. We recommend the use of FC/APC connectors to minimize back reflection of light into the laser. Huber and Suhner part number FCPC-Z/M-A601 are FC/APC narrow key connectors offering >60dB return loss. However, ViaLiteHD supports a range of optical connectors. These vary depending on the product type. Please check the datasheet for each product.

Is it possible to carry multiple carriers having quite different powers beyond a module single range?

The out-of-band performance of the fiber optics links is not specified. Typically, a ViaLite L-Band HTS module will have some response from, say, 400MHz to 2.5GHz and no filtering is included to limit this. It is suggested that if you have out of band signals which might compromise the IP3 of your link then the additiona of a filter or diplexer would improve performance.

Why is gain different on 75 Ohm cards than on 50 Ohm cards?

The cards are built as 50 ohms, we then use a resistive transformer (minimum loss pad) to convert to 75 ohm, which loses 6dB.

Why is gain lower for L-Band HTS cards?

L-Band HTS links use wider bandwidth gain stages. It is therefore not possible to have the same gain.

Why is ViaLite’s dynamic range so large?

We use active biasing & high quality lasers to achieve a very large dynamic range.

What is benefit of a large dynamic range?

Easy set up, good CNR (carrier-to-noise ratio) and good CIR (carrier-to-interference-ratio).

What are the limitations on the test ports?

BNC test ports can be found on the front panel of ViaLiteHD rack chassis cards. 50 Ohm test ports provide a test signal 20dB less than the traffic signal. For 75 Ohm test ports the test signal is 14dB less than the traffic signal on receivers and 26dB on transmitters.

If an LNB noise figure is <1dB and an SSPA is 8dB; how come ViaLite’s noise is good when it is 20dB and why is it not important?

This because there is either (i) gain ahead of the link or (ii) the original signal is relatively high power (Flic’s law).

What is the difference between dynamic range (DR) and spurious free dynamic range (SFDR)?

SFDR is independent of application bandwidth.

What is the limitation of the RF detector on GUI?

P1dB to -30.

Why is the LNB/LNA voltage the same for both channels on a dual card ?

There is only room for one circuit on the current design.

What is the LNB maximum current per channel?

Single channel = 700mA. Dual channel = 350mA.

How many of each card type is needed to not avoid the requirement for a load card?

Combination of cards using >20W.

When might we need to inject voltage into chassis?

If more than 100W is used for powering LNB/LNA’s and redundant PSU’s are still required.

What different options are there for output pin voltage on OEM modules?

Option 0 = 0v. Option 1 = 5v. Option 2 = 12v. Option 3 = supply via rear connector.

 

Can’t find an answer to your question?  Contact us and we will be happy to help.

FAQs
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