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neumoDVB

Configuring the adapters

The terminology may be confusing. According to the DVBS-API documentation, each DVB card in your system is composed of multiple randomly numbered adapters. However, DVB-API does not have the concept of a card and has no idea on whether adapters are on the same or on different cards.

According to DVB-API, an adapter consists of one or more frontends. A frontend is the combination of a tuner, which selects a part of the spectrum and converts it to some base band, and a demodulator which converts the analogue input signal into digital DVB data.

An adapter can have multiple frontends, e.g., to support both terrestrial and satellite reception.

However, in some modern cards like TBS6909X, multiple demodulators can be connected to the same tuner and this connection can even be selected in software. Often this tuner is full band, and selects about 1 Ghz of spectrum and digitizes it. Some more tuning is then done in the digital domain, but this secondary tuning is closely integrated with the demodulator.

The concept of a card is thus essential, because only frontends from the same card can be connected to a band tuner on that card. So neumoDVB adopts as the main concepts: card, tuner, and frontend. A frontend us really only the demodulator (including secondary tuner). As neumoDVB's drivers aim to be compatible with DVB-API, frontends are exposed as devices like /dev/dvb/adapter/0/frontend0, /dev/dvb/adapter/0/demux0, and /dev/dvb/adapter/0/dvr0, with the first one being used to control tuning. How frontends are grouped into adapters is really mostly a choice of the driver developer and so the concept of an adapter is not very useful (except to find out where the frontends are in the device file system).

Configuring the frontends

The first test you should now perform is to check whether neumoDVB can access your DVB devices. From the lists menu, choose Frontends (Ctrl-Shift-F). For each frontend in /dev/dvb/adapterx/frontendy one entry should be listed.

Frontends

Most of the columns provide information, but a few columns can be edited. In order to edit these values, you first need to enable Edit mode (Ctrl-E).

Rows in red are for frontends that once were in the computer, but are not available for some reason, e.g., because the card is not in the system, because the drivers are not loaded, or because some other program is using the frontend or another frontend on the same adapter.

The columns are:

  • adapter. Identifies a DVB adapter. The number after A is the linux adapter number, which can change between boots if cards are removed or added. neumoDVB detects such changes and adjusts the number accordingly. The remaining text shows the name of the card.

  • fe. Frontend number. Some cards have multiple frontends per adapter, which cannot be used simultaneously, e.g. one for DVB-S, and one for DVCB-T/DVB-C. These frontends are numbered starting from 0. The list contains one entry per adapter (not per adapter).

  • card#. Editable Card number. This number is generated by neumoDVB and is used to identify the card in the GUI in places where there is not much space to show the card name. The number is "stable": if you remove the card from the system and later insert it again, the card will still have the same number (unless you deleted the neumoDVB database).

    If for some reason you do not like the auto-generated number, then you can change it. neumoDVB will then use this number for all frontends on the card. If the new number would cause confusion between cards, neumoDVB will renumber the conflicting card.

  • Card. The full name of the card. This is provided as a separate column to allow you to filter the list so as to only display frontends on a s specific card (right click on the column header).

  • Enable. Editable Which DVB standards you want enabled on the card. Usually you want all enabled, but suppose that you have a card which supports DVBT and DVBC. Usually such cards have only one connector shared by DVBT and DVBC. If this connector is connected to a DVBT antenna, then it cannot receive DVBC and you should inform neumoDVB of this by changing the default value "DVB T+C" to "DVB-T". This is essential if you have two such cards in the system, one connected to DVBC and another to DVBT as there is no way for neumoDVB to know which card is connected to which DVB source.

    It is also possible to select None from the list. This is useful if for some reason you want to prevent neumoDVB from using a specific frontend.

  • priority. Editable When neumoDVB has a choice between multiple frontends, it will choose the one with the highest priority. Usually the default value if fine, but if you want to deter neumoDVB from using a specific adapter, e.g., to keep it as much as possible available for other programs, then you can set other frontends to a higher priority.

  • subscription. When a adapter is in use, this column shows what it is used for. In the example, the card is using its first RF connector (#0) to tune 10847V on satellite 28.2E using a Ku band LNB, identified as LNB 1294.

    Subscriptions apply only to neumoDVB, but it is possible to start the neumoDVB program more than once. In this case, subscriptions from all instances will be shown. Such usage has not been well tested and there is usually not much reason for it, but it should work.

  • fe use_count. When neumoDVB needs to tuned to multiple services on the same mux, it uses the same adapter for all of them. This keeps as many as possible frontends and resources free for other uses. The number indicates how many such subscriptions are active.

  • rf inputs. High end cards such as the TBS6909X have more demodulators/frontends (e.g., 8) than tuners (e.g., 4). The tuners are each hard-wired to a specific RF input connector and can capture a full band (1 Ghz wide) of spectrum at once. The cards feature an internal "RF MUX" which allows connecting any demodulator to any tuner. This allows for very flexible use. For instance multiple demodulators can tune to muxes on the same LNB, as long as they are in the same band and have the same polarisation. Also, each frontend can reach all LNBs on all RF inputs.

    The field shows the available RF inputs, e.g. "0 1 2 3". These numbers correspond to the numbers written on the card near each connector (with some exceptions: e.g., for TBS6903X the numbers are 0 and 3 for the first and second connector). Lower end cards do not have an RF mux. In that case the only available input will be "0", but there can be exceptions due to driver limitations.

  • MAC. MAC address of the adapter. This number is supposed to be unique and allows to distinguish multiple cards of the same model in the system. Internally, neumoDVB uses this information to identify the adapter, instead of the linux DVB adapter number.

    As explained above, that DVB-API adapter number can change when cards are removed from or added to the system. In such a case neumoDVB will not be confused because it only uses the adapter number for informational purposes and uses the never changing MAC address to identify the card and its frontends.

    Some cards (e.g., test specimens) do not have a proper MAC address set, or some drivers do not provide this information correctly. In that case neumoDVB generates a fake MAC address, which unfortunately cannot be guaranteed to be stable between boots.

  • Bus. Identifies the linux USB or PCIe bus to which the card is connected for informational purposes only. This will change if you move a card to a different PCIe or USB slot.

  • present. Shows if the adapter is currently in the system. Note that this information is dynamically updated as cards are connected or to or disconnected from the system or as drivers are loaded or unloaded.

  • available. Shows if the adapter is currently available, i.e., not used by other programs or for some reason not usable. Note that this information is dynamically updated.

  • MIS. Shows if the adapter supports multi-stream.

  • blindscan. Shows if the adapter and driver supports blindscan.

  • spec sweep. Shows if the adapter and driver support low resolution spectrum acquisition, typically by sweeping the narrow band analog tuner of the card (if the card has one) or the secondary tuner integrated in the demodulator.

  • spec fft. Shows if the adapter and driver support high resolution FFT-based spectrum acquisition.

  • delsys. Shows the delivery systems (DVB-S, DVB-S2, DVB-T...) supported by the adapter.

The example shows a TBS 6909X card, which has 8 frontends, along with some other cards which are currently not in the system.