NAUTA - Recorders

Recording equipment

Signal recording is needed when on-site real-time analysis is not possible, or/and when it is requested to keep track of the job done, of the detected signals, and when signals require a second analysis.

Nowadays recording systems are really rapidly evolving. Tape recorders are becoming obsolete, with high use cost and poor flexibility, replaced by hard disk recorders, computers and digital interfaces.
Tape recorders are already dead ? Not at all. High quality analog tape recorders, ultrasonic analog tape recorders, digital audio tape recorders (the well known DATs) have still a market quota; but we would not bet on them...

First: know your signal.

If your signal is a low frequency intense vibration, well any recent and decent recording system will do the job. If frequencies are high (let's say over 10 kHz), then things become a bit more complicated, and you do need a quality recording system.

Frequencies are not all, you will also need to check the signal dinamic: How intense will the most intense frequency component of your signal be ? Most digital systems give more than 80dBs of dinamic, some of them more than a hundred. Analog systems can give around 50dBs, more or less, but hardly much more.

When taken to the digital domain, audio signals can be compressed, but is it savvy to compress ?

(keep in ind: we are anyway talking about AUDIO, not ultra-audio (not ultrasounds !). Well, formally ultrasounds can be compressed as well, but a loosy compression algorithm will probably simply cancel the ultrasonic components.)

Then today universally adopted audio compression methods (mp3 and minidisk are two for all) use a psycoacoustic model to take away the part of the signals that will not be heard by the HUMAN listener. If you are recording something that is not music, it is definitely NOT a good idea to compress your signal with such a method.
Too bad.
Portable digital audio recorders, with large hard disks and real-time compression, are a reality that could give a hundred hours of recording time in a pocket. But they have to be considered for what they are.

Looseless compression methods exist. They are "zippers" optimized for audio files. They can save a lot of space on your digital system (something around 50% depending on the file contents). But they are never present on portable devices, and this means that you will need a computer to use a looseless compression.
We like this solution, if space on hard disk is an issue.

During the recent years we used these six methods to record signals.
Are you interested in knowing our comments ?

audio DAT recorder professional and heavy-duty DAT recorder 12VDC modified audio CD burner high quality audio computer interface two-channel high frequency computer interface multi-channel high frequency signal acquisition system

example Sony TCD100 Sony M1, Tascam DAP1 modified
Philips CDR570
EDIROL UA-5
for example
RME or Lynx for example
National Instruments or MOTU audio interfaces

pros It is a standard and has good audio quality.
Tape price is falling if you are using computer tapes.
It is a standard and has excellent audio quality.
Tape price is falling if you are using computer tapes.

These models allow digital copy among tapes.

Has a very low "usage cost".

Recordings can be QUICKLY accessed on CDs.

Easy to use, inexpensive and flexible.
Has a 48kHz of band.
Recordings can be copied to CDs, DVDs and other hard disks.
Indexes are automatically generated while recording.
You see what happens in real-time

Same or better than UA-5, today even to 90kHz of band.

You see what happens in real-time

You will get a multi-channel recording.

You see what happens in real-time

cons
"Audio" tapes are expensive, while "computer" tapes are not (but not every 4mm tape is compatible)
The recorder is quite a delicate instrument.
Digital copy among tapes (for backups) could be impossible if copy protection scheme is adopted.
Tapes must be played back into an acquisition system to analyse signals (and this IS a pain in the neck).

"Audio" tapes are expensive, while "computer" tapes are not (but not every 4mm tape is compatible)
The recorder is quite a delicate instrument.

Tapes must be played back into an acquisition system to analyse signals (and this IS a pain in the neck).

It is a delicate intruments, that must not vibrate while recording.

Modifying the unit is not easy.

You will need a computer with a USB interface and a large hard disk.
A laptop is ok.

You will need to make back-up copies.

You will need a desktop computer and LARGE hard disks.

You will need a backup system.

You will probably need an external signal conditiong system (filtering, level adjusting, ...)

You will need a computer, XLARGE hard disks and a backup system

indicative prices 850 € 900 - 2500 € 400 € + modification
We like this !

we sell the UA-5 at 330 €
500€ to 1200€ 2000 - 3000 €

Recording equipment
	Signal recording is needed when on-site real-time analysis is not possible, or/and when it is requested to keep track of the job done, of the detected signals, and when signals require a second analysis. Nowadays recording systems are really rapidly evolving. Tape recorders are becoming obsolete, with high use cost and poor flexibility, replaced by hard disk recorders, computers and digital interfaces. Tape recorders are already dead ? Not at all. High quality analog tape recorders, ultrasonic analog tape recorders, digital audio tape recorders (the well known DATs) have still a market quota; but we would not bet on them...
First: know your signal.
	If your signal is a low frequency intense vibration, well any recent and decent recording system will do the job. If frequencies are high (let's say over 10 kHz), then things become a bit more complicated, and you do need a quality recording system. Frequencies are not all, you will also need to check the signal dinamic: How intense will the most intense frequency component of your signal be ? Most digital systems give more than 80dBs of dinamic, some of them more than a hundred. Analog systems can give around 50dBs, more or less, but hardly much more.
	When taken to the digital domain, audio signals can be compressed, but is it savvy to compress ? (keep in ind: we are anyway talking about AUDIO, not ultra-audio (not ultrasounds !). Well, formally ultrasounds can be compressed as well, but a loosy compression algorithm will probably simply cancel the ultrasonic components.) Then today universally adopted audio compression methods (mp3 and minidisk are two for all) use a psycoacoustic model to take away the part of the signals that will not be heard by the HUMAN listener. If you are recording something that is not music, it is definitely NOT a good idea to compress your signal with such a method. Too bad. Portable digital audio recorders, with large hard disks and real-time compression, are a reality that could give a hundred hours of recording time in a pocket. But they have to be considered for what they are.
	Looseless compression methods exist. They are "zippers" optimized for audio files. They can save a lot of space on your digital system (something around 50% depending on the file contents). But they are never present on portable devices, and this means that you will need a computer to use a looseless compression. We like this solution, if space on hard disk is an issue.

	audio DAT recorder	professional and heavy-duty DAT recorder	12VDC modified audio CD burner	high quality audio computer interface	two-channel high frequency computer interface	multi-channel high frequency signal acquisition system
example	Sony TCD100	Sony M1, Tascam DAP1	modified Philips CDR570	EDIROL UA-5	for example RME or Lynx	for example National Instruments or MOTU audio interfaces
pros	It is a standard and has good audio quality. Tape price is falling if you are using computer tapes.	It is a standard and has excellent audio quality. Tape price is falling if you are using computer tapes. These models allow digital copy among tapes.	Has a very low "usage cost". Recordings can be QUICKLY accessed on CDs.	Easy to use, inexpensive and flexible. Has a 48kHz of band. Recordings can be copied to CDs, DVDs and other hard disks. Indexes are automatically generated while recording. You see what happens in real-time	Same or better than UA-5, today even to 90kHz of band. You see what happens in real-time	You will get a multi-channel recording. You see what happens in real-time
cons	"Audio" tapes are expensive, while "computer" tapes are not (but not every 4mm tape is compatible) The recorder is quite a delicate instrument. Digital copy among tapes (for backups) could be impossible if copy protection scheme is adopted. Tapes must be played back into an acquisition system to analyse signals (and this IS a pain in the neck).	"Audio" tapes are expensive, while "computer" tapes are not (but not every 4mm tape is compatible) The recorder is quite a delicate instrument. Tapes must be played back into an acquisition system to analyse signals (and this IS a pain in the neck).	It is a delicate intruments, that must not vibrate while recording. Modifying the unit is not easy.	You will need a computer with a USB interface and a large hard disk. A laptop is ok. You will need to make back-up copies.	You will need a desktop computer and LARGE hard disks. You will need a backup system.	You will probably need an external signal conditiong system (filtering, level adjusting, ...) You will need a computer, XLARGE hard disks and a backup system
indicative prices	850 €	900 - 2500 €	400 € + modification	We like this ! we sell the UA-5 at 330 €	500€ to 1200€	2000 - 3000 €