Net-Log

A four-channel digital audio encoder and storage unit designed to overcome the compromises of PC-based recording. Conceived for recording (“logging”) the output of radio stations, the unit is also suitable for more general audio archive applications that would benefit from the remote access feature. Using dedicated hardware in a single rack unit case, Net-log is controlled and accessed via a TCP/IP network using PCs running dedicated software.

The inputs can be configured for mono, dual-mono or stereo sources; the audio data is stored on an internal disk-drive using the MPEG Layer-2 format as standard, however an optional G.729 codec is available for use (see Recording paragraph for further details). A wide range of bit-rates and encoding configurations are possible to maximize the effectiveness of the available storage. Although the internal disk could retain the encoded audio for some time before being overwritten, recordings would normally be saved on external storage media , usually a file server, if they are required for long-term use. Each Net-log is assigned a unique IP address, so more than one unit can be connected to a network.

The unit is designed for storage only. To access the audio a TCP/IP network is required, and a PC running Net-Log-Win software (supplied separately). This application is required to configure the network settings, the input channels, the recording schedule and the archiving routines. Software and firmware have been designed to be resilient to power failures, and a secure password control scheme prevents unauthorized tampering with the configuration. Except for one button to activate recording in an emergency, there is no means of accessing the unit from the front panel, although as an aid to maintenance, LEDs indicate the audio levels, archive alarm and if a disk fault is detected. Serial control code has been added so that recording can be controlled by AMX, Crestron and Televic (meeting room & board room) controllers.

Recording

An integral, 1 terabyte disc drive will store many timed recordings of each channel. The following assumes this disk capacity. (See Ordering Note below.) When the hard disk is full, the oldest data is overwritten. It is possible to store around one year of low bit-rate audio and several days of high-quality stereo audio at the same time. For example, a radio station could use one unit to record and store a reduced quality recording of its output to meet regulatory requirements, and use a short-term, high-quality recording for a production resource. The recording process can be activated over the network using the Net-Log-Win software, or from the remote-control connector, so the unit could be configured to save the speech output from live microphones or by audio presence. All recordings are time-referenced to an internal clock, or synchronized to an external time standard over the network. Net-Log can be programmed to start & stop recording at different times and up to 250,000 recordings per channel can be made. Record input levels can be altered via rotary potentiometers and recordings can optionally be made using G.729 as the recording algorithm, allowing longer recordings, lower network traffic and almost instantaneous playback. However, this codec must be purchased separately, as a separate licence.

Playback

The Net-log-Win software, available separately, allows authorized users to access the record units over a network using the TCP/IP protocol. Recordings can be either streamed directly to the PC depending on the recording bit-rate and network load, or downloaded to the PC for saving as MPEG Layer 2 (MP2), or a Broadcast Wave Format (BWF) sound files. Once archived, the audio can be replayed from any PC equipped with a compatible sound card and appropriate decoding software. The support software also allows near real-time listening to any source connected to a record unit on the network. Net-Log-Win software is for use with Windows XP/Vista/7.

The Ethernet network connection is presented on RJ45 or BNC connectors on the rear panel, with two pairs of three-pin XLR connectors for the audio inputs. A 15-way D-Sub female connector allows each individual channel to be switched into record mode remotely, depending on the configuration. A combined hard-disk and archive alarm signal is available on the remote connector to operate external sounders or indicators. Two 9-pin D-sub serial communications ports are provided to load firmware upgrades, and for setting the network parameters of the unit.

Technical Specification:

Maximum number of channels:	Four mono or two stereo
Audio input impedance:	>10kohm, balanced
Input gain adjustment:	-6 dB to +20 dB ref Full-scale digits
Distortion:	<0.1 % at 1 kHz, +16 dBu
Signal to noise ratio:	90dB RMS A-weighted (22 kHz bandwidth)
Maximum input level:	+20 dBu
Audio coding:	MPEG I Layer 2
Sample rates:	16, 22.05, 24, 32, 44.1and 48 kHz
Available bit rates:	Mono: 8 to 192kbit/sec; Stereo: 8 to 384kbit/sec
Audio modes:	Mono, Dual Mono, Stereo
Storage capacity:	1TB minimum. See Ordering Note below

Network protocol:	TCP / IP
Network connections:	Ethernet, 10BaseT (RJ45) or 10Base2 (BNC), 10 MBps
Device addressing:	Class A, B or C, (requires a fixed IP address )

Remote Connector:	Recording control: Momentary, or latching start command for each channel
External Alarm Output:	Two relay contacts for combined disk failures and archive warning

Power Supply:	95 – 265V AC, 47-63 Hz (IEC connector)
Dimensions:	1U rack-mounting x 220mm deep
Net weight:	2.5 kg