Traditionelle "Humbucker" bzw. Isolationsübertrager-Lösungen sind für SDI-Signale üblicherweise nicht anwendbar. Netzbrumm liegt frequenzmäßig weit unter dem SDI-Signalfrequenzspektrum, und – anders als bei analogem Video – das SDI-Signal ist unempfindlich gegen starke Dämpfung Richtung niedrigster Freqzenzen bzw. Gleichspannung. Jedoch stellen Verzerrungen sowie große Spannungssprünge bzw. Potentialdifferenzen zwischen zwei miteinander verbundenen SDI-Geräten nach wie vor ein Problem dar.
SDI Isolatoren, die Gleichstrom aus den Signal- und Erdungswegen herausfiltern, werden in vielen Ü-Wagen eingesetzt. Diese Produkte sind insbesondere in trockneren Regionen der Welt eingesetzt. Hier kann das Erdungspotenzial über längere Kabelstrecken viele Volt betragen, wodurch die Gefahr einer Beschädigung der empfindlichen Koppelkondensatoren am Eingang von Geräten besteht.
The L E N ground isolators use broadband high-pass filters to provide complete galvanic isolation of DC currents between two pieces of equipment, whilst permitting the full bandwidth of the SDI signal to pass, thus avoiding problems of signal distortion and operator shocks caused by a voltage difference. This method out-performs broadband transformers for SDI signals. Both signal and ground paths between equipment are isolated, there is no distortion of the signal. They are suitable for ASI format.
There are three ranges with different housings; one range has encapsulated enclosures which may be rack-mounted with an accessory panel, one has in-line 'barrels', with or without a mounting flange, the third offers designs with higher breakdown voltage for medical grade applications - see LEN VIDEO FILTERS - MEDICAL GRADE - SD, HD, 3G, 4K/12G SDI ground isolation, and are available both constructed in ABS boxes with mounting flanges and as ‘barrel’ versions, with or without a mounting flange.
Common specifications are as follows. Input and output impedance: 75 ohms. Return loss: Better than 20dB.
Note 1: These are minimum values.
Encapsulated Enclosure - L3GF01, LHDF01
L3GF01 may be used with 3G, HD or SD SDI signals while the LHDF01 may be used with HD or SD SDI. Each is built in an ABS enclosure fitted with two female BNC connectors. Two M3 mounting screws are provided on the same face as the connectors, so that the filters can be mounted flat to a panel, with the connectors protruding through it.
Dimensions: 45 x 30 x 15 (l x w x h) mm. Weight: 26g.
Optional accessories: The LMPF01 rack frame is a 1U 19-inch panel, finished in black, punched to take eight filters mounted from the rear by means of the mounting screws, the BNC connectors facing out of the rack. If it is desired to have the connectors facing into the rack, the filters may be reversed, revealing the filter modules which will protrude 15mm from the surface of the panel.
In-line 'Barrel' Type – L4KGIO1, L3GGI01, LHDGI01
L4KGI01 is for use with full 12G/4K UHD SDI video and all lower standards including 6G, 3G, HD and SD SDI. L3GGI01 may be used with 3G, HD or SD SDI signals while the LHDGI01 may be used with HD or SD SDI.. They are built in cylindrical plastic (for isolation) enclosures, fitted with a BNC connector at each end. They are ideal for carrying in a toolbox, to cure interference issues.
Dimensions: 30 x 20 (l x diameter) mm. Weight: 36g.
In-line 'Barrel' Type, with mounting flange for through panel mount L4KGIO2, L3GGI02, LHDGI02
L4KGI02 is for use with full 12G/4K UHD SDI video and all lower standards including 6G, 3G, HD and SD SDI. L3GGI02 may be used with 3G, HD or SD SDI signals while the LHDGI02 may be used with HD or SD SDI.. They are built in cylindrical plastic (for isolation) enclosures, fitted with a BNC connector at each end An industry-standard size mounting flange is fitted at one end.
Dimensions: 30 x 20 (l x diameter) mm, mounting flange 31 x 26 mm. Weight: 37g.
Optional accessories: LMPG01 rack frame is a 1U 19-inch full width panel, finished in black, punched to take sixteen isolators mounted from the rear by means of the mounting flanges, so that the BNC connectors are on either side of the rack. LMPG02 rack frame is a 1U 19-inch half width panel, punched to take eight isolators, mounted in the same way as the full width panel.