Digital voice recording
Telephone lines of workplaces, microphones of conference and exchange halls, radio channels of dispatcher and lifeguard services etc. can be recorded and saved for long time by digital voice loggers continuously unattended. In contrast with traditional tape-recorders the digital voice loggers use large capacity data medias for storage, so less time needs to be spent for maintenance.
If an office has e.g. 4 telephone lines and the summed talk time is 1.5 hours/telephone line/day, the hard disk of even the smallest capacity CCRL voice logger (2100 hours storage time) can store the recordings of almost one year. Due to the automatic circulating voice recording the storage process need no supervision. If the longer storage time or the increased safety is the goal, the recordings can be stored by the automatic backup function of the voice loggers on modern storage medias for years, and the task of operator is only replacing the backup media.
Recently the price is lowered and the storage capacity is increased significantly on the market of digital voice loggers, so the price / power ratio decreased on the market of voice loggers. The Windows base CCRL voice loggers can use these modern, large capacity medias (e.g. DVD, external USB drive, pen drive etc.) for storage and backup.
The digital voice loggers decode and compress the telephone calls from data stream of ISDN30 / ISDN2 (PRI/BRI ISDN) telephone trunks and digital extensions of PABXs and sample, digitalize and compress the signals of analogue PSTN lines, extensions and other signal sources (microphone, radio). The compressed data are stored in files on the hard disk of the computer. (With appropriate interface any analogue signal can be sampled, digitalized and stored.)
Without compression the PCM data rate is 64 KBit/sec. Our voice loggers reduce the data rate to 36/16/8 KBit/sec with special ADPCM compression (good telephone voice quality and economical storage). The capacity growth of hard disks, the better price / capacity ratio and the fact that in Windows system there is no practical storage capacity limit provide facilities for using the better voice quality 36 KBit/s compression.
In Windows system the limit of hard disk capacity is much higher than the DOS limit and hard disks provide far larger storage area too, so the storage time of the voice loggers that record without supervision automatically, increased significantly. The 4.600 hours storage time of the DOS voice loggers (16 KBit/s, 7.2 MByte/hour) increased to 120.000 hours in case of a professional CCRL Pro voice logger with 4 pc 500 GByte hard disk(36 KBit/s, 16.2 MByte/hour) and meanwhile the quality of voice recordings even got better.