AUDIO CLOCK GENERATION
The standard 44.1, 88.2 , 48 and 96 kHz audio clocks are generated directly from discrete crystal oscillators working in fundamental mode without DDS (direct digital synthesis) or PLL (phase locked loop) circuits in the clock signal path.
This vintage technology is not as universal as today's digital clock synthesis circuits because it is limited to only one sample rate (+/- 50ppm) per crystal oscillator, but on the other hand it still provides the purest clock quality with lowest phase noise.
Nanoclocks GL also generates -0.1% pull down sample rates using fractional division and a very high frequency PLL circuit.
REFERENCE = INTERNAL
Audio crystal oscillators are tuned to a TCXO timebase accurate to 0.2 ppm.
REFERENCE = VIDEO
Audio crystal oscillators are locked to
external SD video syncs with 23.98, 24, 25 (PAL) or 29.97 (NTSC) fps or
HD tri-level syncs with 23.98, 24, 25, 29.97, 50, 59.97 or 60 fps.
All SD/HD video frame rates and standards are detected automatically.
Where possible, audio clocks will also be phase locked to video v-syncs (requires a whole-number proportion of sample rate and frame rate). Two reference inputs provide automatic switchover in case of one reference signal fails.
REFERENCE = AUDIO
Audio crystal oscillators are tuned to external word clock or AES-11 DARS signals.
Automatically follows 44.1, 48, 88.2, 96 kHz and -0.1% pull down sample rates.
Lock range is +/- 50ppm.
The audio reference signals are used to synchronise the internal audio crystal clock generators accordingly, so clock quality is not affected by incoming jittery reference signals.
Select signal from input A or B manually or use the automatic switchover functionality.
REFERENCE = DISTRIBUTION AMPLIFIER
Word clock or AES11/ DARS signals on inputs A and B are directly routed to all 12 outputs.
Detected sample rates are displayed and outputs are switched to word clock or AES11 levels according to the present input signal. This mode also distributes all word clock/AES11 signals at non-standard sample rates, i.e. 50kHz.
TERMINATION AND OUTPUT MODE
The connection status of the each clock outputs can be monitored by 12 LEDs:
off: output is open
green: 75Ω terminated
red: double, low terminated.
The output mode of each individual output can be set to word clock, AES11 DARS or a user programmable signal.
The unit can be controlled and its firmware can be updated via USB MIDI.
When synchronising audio clocks to video syncs or other reference signals, it is important not to track disruptions or glitches, to hold and maintain phase lock, to hold the actual tuning when the reference signal fails and to relock very smoothly.
For many years, Rosendahl Studiotechnik has been developing and improving software algorithms to synchronise clocks together.
The unit can be supplied by mains (115/230 VAC switchable) and/or 12V DC using a 4-pin XLR connector, which provides a redundant power system if both power sources are being used.
The AC power supply uses a vintage (again!) mains transformer combined with a power saving secondary switching regulator.
It is designed for maximum reliability and life span. We know that a reliable master clock generator is an essential part of any studio.
nanoclocks GL consumes 7 watts only. With one unit running 24/7 for 10 years, this results in 613 kWh or 215.-€ (at 35ct/kWh) of consumed energy.