Transient recorder model selection

model name TR 40-16bit-3U-opt.

The units have 32k memory, which can be configured by the user for shorter memory depths. The oversampling can also be configured by the user so that 20MHz, 10MHz, 5MHz, 2.5MHz and 1.25MHz sampling rates can be achieved while keeping the number of bins constant. Per default the units ship with a 16k trace length and sampling speed of 40MHz.

In order to change the transient recorder default memory length you need to unmount the transient recorder first (see the for mounting instructions).

Then open the side panel.

For TR 40-16bit-3U-opt the address switch is in the lower middle of the board. address swithc location

The black dip switch for the address selection also hosts the memory length selection, the following lengths can be selected.

memory depth	6	7	8	Sample	16k Address 0
512	OFF	OFF	OFF
1k	ON	OFF	OFF
2k	OFF	ON	OFF
4k	ON	ON	OFF
8k	OFF	OFF	ON
16k	ON	OFF	ON
32k	OFF	ON	ON

Transient recorder memory/range resol./repetition rate

	sample rate	10	20	40	80	MHz
memory	range resol.	15	7.5	3.75	1.875	m
256	max. rep. rate	31.25	52	78	103	kHz
256	max signal	3.84	1.92	0.96	0.48	km
512	max. rep. rate	15.6	26	39	51	kHz
512	max signal	7.68	3.84	1.92	0.96	km
1K	max. rep. rate	7.81	13	19.5	25.9	kHz
1K	max signal	15.36	7.68	3.84	1.92	km
2 K	max. rep. rate	3.90	6.5	9.75	13	kHz
2 K	max signal	30.72	15.36	7.68	3.84	km
4 K	max. rep. rate	1.95	3.25	4.88	6.5	kHz
4 K	max signal	61.44	30.72	15.36	7.68	km
8 K	max. rep. rate	0.97	1.62	2.44	3.2	kHz
8 K	max signal	122.88	61.44	30.72	15.36	km
16 K	max. rep. rate	0.48	0.81	1.22	1.6	kHz
16 K	max signal	245.76	122.88	61.44	30.72	km
32 K	max. rep. rate	0.24	0.40	0.61	0.81	kHz
32 K	max signal	491.52	245.76	122.88	61.44	km

with 10 kHz Laser the following trace lengths will work

sample rate	10 MHz	20 MHz	40 MHz	80 Mhz
bins	750	1300	1950	2660
tracelength (km)	11.25	9.75	7.3	4.9

To work with these tracelengths set the DIP Switch 5, which turns the configurable tracelengths on, to ON.

options:

AP: separated inputs for analog and photon counting. Makes sense for APD users who also detect weak PMT signals (Raman signals, etc). One trigger source - two detectors (APD + PMT in photon counting). See also situations when this is not a good option

AP Considerations

There are situations where the AP option looks like a economic good idea at first glance but the side effects are unwanted

Depolarization: Use analog for the strong parallel and photon counting for the weak depol. channel. This works as long as you do not hit an strongly depolarizing ice cloud...
N₂ in water raman system: You typically send so much light out at 355 to see a water raman signal that the N₂ which has 3 orders of magnitude more cross section would require a neutral density filter, where the expensive photons that your system emits, have to die to make the photon counting possible
Daytime water raman (408nm): 408nm is not in the solar blind region any more, so typically your background signal goes up when the sun rises. If this signal background exceeds 60 MHz (roughly 1 mV with our PMT) the dead time correction for this is already significant. But more sadly most of your linear dynamic range of the photon counting has gone. Dead time correction after 90 MHz of observed count rate is far beyond where the photon counting dead time correction theory applies:
(90MHz / 300MHz is not << 1)

Previous Transient recorder models

model name TR XX-YYY-opt.

XX	=	sample rate (for analog and photon counting), defines the ADC clock and photon counter readout cycle time.
20	=	20 MHz, standard (7.5 m range resolution)
40	=	40 MHz, for high resolution systems (3.75 m range resolution)

lower sample rate is possible, but it limits the max. average photon count rate (not the pulse pair resolution)

YYY	=	FIFO memory length, defines the max. signal length and the max. repetition rate
160	=	16384 databins, standard, lidar signals up to 819.2µs or 122.88 km, max. rep. rate=300 Hz.
80	=	8192 databins, lidar signals up to 409.6µs or 61.44 km, max. rep. rate=610 Hz.

for other combinations see list below.

options:

AP	=	separated inputs for analog and photon counting. Makes sense for APD users who also detect weak PMT signals (Raman signals, etc). One trigger source - two detectors (APD analog + PMT in photon counting).
opt.	=	optical trigger input.(Trigger source is a SMA Emitter). Additional galvanically decoupling. Only for very noisy laser sources (Excimer, flashlamp pumped Ti:Sapphire lasers). Our standard electrical trigger is already galvanically decoupled.
las	=	optical trigger with laser pulse as trigger source. Includes a photodiode and a fast Schmitt Trigger with variable threshold. Application: Passive Q-switched lasers (mini lidars).

Memory selection chart

Note: Starting from October 2009 all TR units will have a 64k memory, which can be configured by the user for shorter memory depths.

The black dip switch for the address selection also hosts the memory length selection, the following lengths can be selected.

memory depth	6	7	8
512	OFF	OFF	OFF	16k Address 0
1k	ON	OFF	OFF
2k	OFF	ON	OFF
4k	ON	ON	OFF
8k	OFF	OFF	ON
16k	ON	OFF	ON
32k	OFF	ON	ON
64k	ON	ON	ON

Transient recorder memory/range resol./repetition rate

	model No.	TR 10	TR 20	TR 40	unit
	sample rate	10	20	40	MHz
memory	range resol.	15	7.5	3.75	m
256	max. rep. rate	15.62	19.53	22.32	kHz
256	max signal	3.84	1.92	0.96	km
512	max. rep. rate	7.81	9.76	11.16	kHz
512	max signal	7.68	3.84	1.92	km
1K	max. rep. rate	3.90	4.88	5.58	kHz
1K	max signal	15.36	7.68	3.84	km
2 K	max. rep. rate	1.95	2.44	2.79	kHz
2 K	max signal	30.72	15.36	7.68	km
4 K	max. rep. rate	0.97	1.22	1.39	kHz
4 K	max signal	61.44	30.72	15.36	km
8 K	max. rep. rate	0.488	0.61	0.69	kHz
8 K	max signal	122.88	61.44	30.72	km
16 K	max. rep. rate	0.17	0.30	0.34	kHz
16 K	max signal	245.76	122.88	61.44	km

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