Compact Headends - FAQ & Answers

The three product series differ mainly in their output signals and equipment.

• QAM series: Conversion of satellite signals into DVB-C.
• PCU series: Output optionally as DVB-C or DVB-T.
• PXU series: Like the PCU series, additionally with integrated input multiplexer.

Both devices offer eight output channels and an output level of up to 90 dBµV. The main difference lies in the SAT feed: while the PCU 8510 requires eight individual SAT feeds, the PCU 8610 has an integrated 4×8 multiswitch. As a result, four SAT feeds are sufficient, which significantly reduces installation effort.

The following devices have triple tuners for mixed operation:

• 4 tuners: PCU 4111, 4121, 4131, 4141
• 8 tuners: PCU 8112, 8122, 8130, PXU 848 C/T/IP

The triple tuners enable reception of DVB-S/S2, DVB-T/T2 or DVB-C signals as required.

Yes. Several POLYTRON compact headends can be cascaded to form a common system. Thanks to adjacent-channel operation and a shared NIT, the entire programme offering appears as a single continuous network during channel search. This allows extensive systems with more than 100 TV programmes to be realised.

POLYTRON recommends conversion to DVB-C. Significantly more programmes can be transmitted per output channel. Conversion to DVB-T only makes sense if the end devices do not have a DVB-C tuner.

Yes. Depending on the application, Sky programmes can be decrypted centrally or fed into the network in encrypted form.

• Central decryption: Using a CI module and a suitable Sky Hospitality subscription.
• Encrypted forwarding: The programmes are transmitted unchanged to TVs or receivers and decrypted there.
• The following compact headends are equipped with four CI slots each: PCU 4111/4121/4131/4141, PCU 8112/8122, PXU 848 C/T/IP.

Which output type is suitable depends primarily on the existing infrastructure and whether it is an existing building or a new build.

Coax (DVB-C) is usually the best solution for existing antenna distributions. TVs can be used without additional set-top boxes and a high programme capacity is available.

IPTV is particularly suitable for new builds or fully IP-based networks. TV services can be integrated flexibly into existing network infrastructures.

Yes. The devices are delivered with a preconfigured transponder list for Astra 19.2° East and are therefore quickly ready for operation.

If a different channel line-up is required, it can be adjusted at any time via the web interface or the free SATC12 software.

Yes. POLYTRON compact headends are operated worldwide under a wide range of climatic conditions. They are designed and manufactured to operate reliably even under extreme conditions.

POLYTRON compact headends can be operated at ambient temperatures between 0 and 50 °C. ISO 9001 certified manufacturing at the production site in Bad Wildbad ensures that POLYTRON compact headends “Made in Germany” achieve an exceptionally long service life.

Configuration depends on the respective product series.

• IPTV streamers: Setup via the integrated web interface in the browser.
• DVB-C/DVB-T compact headends: Configuration via the free Windows software SATC12.

For setup, the compact headend is connected directly or via the network to the laptop.

• IPTV streamers: Connection via LAN (RJ45) and a compatible web browser.
• DVB-C/DVB-T headends: By default via USB, and on current models additionally via LAN.

Configuration is carried out via a current standard web browser. For optimal display, it is recommended to use an up-to-date browser version.

Yes, as soon as the device is integrated into a network and appropriate remote access to the network is available. The exact procedure depends on the existing network infrastructure. Please consult the responsible local IT administrator.

For basic device settings, no active signal feed is required. For analysis and programming of reception parameters, the corresponding signal source must be connected.

Yes. Saved configurations allow quick transfer of proven settings to additional devices or follow-up projects.

Backup and restore are carried out via: Settings → Save Settings / Load Settings.

The latest software versions and version information can be found in the POLYTRON download area at https://www.polytron.de/de/service/download.

• IPTV streamers: The current software package is available directly for download.
• DVB-C/DVB-T headends: The software versions are part of the installation package of the SATC12 programming software.

First check the USB connection and make sure the device is correctly powered. If necessary, reinstall the latest version of the SATC12 software and the USB driver.

First check whether the laptop and the compact headend are in the same network.

• Make sure your laptop has an IP address in the same subnet as the headend.
• By default, the network 192.168.1.xxx / 255.255.255.0 is used.
• The preset IP address of the respective device can be found in the corresponding operating manual.
• If the compact headend is integrated into a local network, please contact the responsible IT administrator.

These messages indicate that the input tuner is not receiving a usable input signal or cannot synchronize to the desired transponder. The cause usually lies in the signal feed, reception settings or supply of the signal source.

For “Tuner unlocked”, check:

• Is the correct reception frequency or the correct transponder configured?
• Do symbol rate and modulation parameters match the input signal?
• Is the connected satellite or signal source correctly selected?
• Is there sufficient signal level and signal quality at the input?

For “No Signal”, additionally check:

• Is the signal feed correctly connected?
• Is there actually an RF signal present at the tuner input?
• For SAT reception: Are LNB supply and DiSEqC settings correct?
• For multiswitch systems: Are the correct SAT bands connected?
• For DVB-T/T2: Is antenna supply or 5 V supply configured correctly?

Technical background:

• “Tuner unlocked” means: The tuner detects a signal but cannot establish a stable synchronization with the transport stream.
• “No Signal” means: No usable signal is detected at the input.

“Tuner locked” indicates that the input transponder is being received and synchronized successfully. Via the context menu Service List you can then check the received programmes.

The Input Service List contains all services received by the tuner. The Output Service List shows the programmes that are mapped for output.

If the Output Service List is empty, check the following points:

• Are programmes present in the Input Service List?
• Have the desired services been selected or transferred for output?
• Is the chosen output type (DVB-C/DVB-T/IP) sufficiently dimensioned for the desired number of programmes?
• For DVB-T output: Is the available output bandwidth sufficient for the selected services?

Note: For DVB-C output, the Output Service List is usually filled automatically with the available services because the available bandwidth allows an extensive programme line-up. In case of limited output capacity, for example in DVB-T implementations, selection or reduction of services may be necessary.

An inserted CI module alone is not sufficient to decrypt programmes. First check the CAM status in the diagnostics and then the assignment of the services to be decrypted.

In the CAM diagnostics, the individual steps are indicated with a green tick or a red X:

• CAM plugged: The CI module has been detected and is physically inserted.
• CAM initialized: The CI module has been successfully initialised and is ready for operation.
• Descrambling: The programme is currently being decrypted by the CAM.

If any of these steps is indicated with a red X, the cause lies in the corresponding step.

In addition, the programme must be selected for decryption in the Output Service List:

• Enable the checkbox for the programmes that are to be decrypted via the CI module.
• Then check the Descrambling status in the diagnostics.

Note: A detected and initialised CAM does not automatically decrypt all available programmes. The desired services must be selected for decryption and assigned to CI processing.

Pixelation in the output signal usually indicates a disturbance in the transmitted data stream. In POLYTRON compact headends there are mainly two causes:

1. The available useful bandwidth is fully utilised (overflow)

If the sum of the data rates of the selected services exceeds the available output bandwidth, an overflow may occur. This can result in picture disturbances, block artefacts or dropouts on individual programmes.

Check:

• Is the available output bandwidth sufficient for the selected TV programmes?
• Have additional HD programmes or data-intensive services been added?
• For DVB-T output: Are too many or too data-intensive services placed on a single channel?
• Are unneeded services deactivated in the output line-up?

2. Disturbances or frequency conflicts in the distribution network

Incorrect output planning or disturbances in the coaxial network can also cause pixelation.

Check:

• Are there interfering carriers in the used frequency range?
• Are output frequencies used twice by several headends or components?
• Are the output channels correctly planned and sufficiently separated from each other?
• Are the output levels of the headend and subsequent network components set correctly?

Note:
For digital TV signals, quality problems often appear as block artefacts or short interruptions. Increasing the output level does not eliminate the cause if it is due to bandwidth overflow or disturbances in the distribution network.

With IPTV, pixelation and brief dropouts are often caused by faulty transmission of multicast data streams in the network. In addition to network load, IGMP configuration is particularly important.

Check the following points:

1. IGMP snooping is not correctly enabled in the network

IPTV streams are usually transmitted as multicast. Without correctly configured IGMP snooping, switches cannot forward data streams specifically to the participants that require them.

Possible effects:

• Unnecessary load on the network due to multicast streams that are not needed
• Packet loss
• Picture disturbances or dropouts

Check:

• IGMP snooping status: Is the function enabled globally on all switches involved in the data path and for the specific IPTV VLAN?
• IGMP querier configuration: Is at least one switch (or router) in the network configured as an active querier to update the multicast tables cyclically?
• Switch load (CPU/RAM): Do network components show increased load due to processing uncontrolled data streams?
• Port statistics: Are there packet losses (drops/discards) or CRC errors at subscriber ports?
• Multicast distribution: Are IPTV streams incorrectly forwarded to ports where no IPTV receiver (set-top box) is active?
• VLAN configuration: Are IPTV multicast streams cleanly separated from other data traffic in a dedicated VLAN?

2. Network components do not support or process multicast correctly

Check:

• Do the switches used support IGMP snooping?
• Is IGMP snooping enabled on the relevant ports?
• Is there an IGMP querier in the network if required?
• Are VLANs and network settings used correctly?

3. Network bandwidth or data rate is not sufficient

High network utilisation can also lead to disturbances.

Check:

• Is sufficient bandwidth available between the IPTV streamer and end devices?
• Are there packet losses or high network load?
• Are unnecessary multicast streams being distributed in the network?

Note:
In IPTV, faulty multicast distribution often does not lead to a complete failure, but initially to block artefacts, short picture dropouts or frozen images.