[time-nuts] Ultra High Stability Time Base Options for 53132A

Hans Holzach hans.holzach at gmail.com
Wed Apr 22 06:17:38 EDT 2015


during the last days i ran a few tests with different high stability 
options.

setup:
channel 1: thunderbolt 10 mhz divided down to 1 pps
channel 2: trimble 73090 DOCXO 10 MHz divided down to 1 pps. frequency 
offset about 7e-9
internal time bases: no additional time base; morion mv89a; trimble 34310-t
external time bases: no external time base; thunderbolt 10 mhz
tapr distribution amplifier, tapr frequency dividers

strong temperature swings in the attic, about 10°C, thunderbolt not 
protected, trimble 73090 (channel 2) in box with a lot of small water 
containers.

internal time base: NO high stability time base, external time base: NONE
adev: https://farm9.staticflickr.com/8742/17196609681_53937b7e5d_b.jpg
spectral density: 
https://farm8.staticflickr.com/7688/17197584451_50e359e46f_b.jpg

internal time base: NO high stability time base, external time base: 
thunderbolt 10 mhz
adev: https://farm8.staticflickr.com/7587/16997478560_1a422eb0f2_b.jpg
spectral density: 
https://farm8.staticflickr.com/7604/17159258816_743ba1f83a_b.jpg


internal time base: morion mv89a, external time base: NONE
adev: https://farm9.staticflickr.com/8802/16962399320_908fea406c_b.jpg
spectral density: 
https://farm6.staticflickr.com/5349/16565001513_e3f47482e6_b.jpg

internal time base: morion mv89a, external time base: thunderbolt 10 mhz
adev: https://farm9.staticflickr.com/8774/16949313140_29937eb5d6_b.jpg
spectral density: 
https://farm6.staticflickr.com/5346/17159259246_eb20993753_b.jpg


internal time base: trimble 34310-t, external time base: NONE
adev: https://farm9.staticflickr.com/8816/17232552925_4f4e9bc267_b.jpg
spectral density: 
https://farm8.staticflickr.com/7644/17044785268_bdb5b2fa97_b.jpg

internal time base: trimble 34310-t, external time base: thunderbolt 10 mhz
adev: https://farm9.staticflickr.com/8784/16602405264_41fefbed43_b.jpg
spectral density: 
https://farm9.staticflickr.com/8710/16604641953_de800d9769_b.jpg


more plots (phase and autocorrelation samples) at: 
https://www.flickr.com/photos/olmstead/collections/72157651929343312/

looking at the ps plots: it seems to be a good idea not to use a high 
stability time base if an external time base like a thunderbolt is 
plugged to the counter. both external and internal time bases seem to 
add a lot of spurs to the power spectrum, at least in my setup with my 
gear. ugliest combination is a morion high stability time base AND an 
external time base.

best regards,
hans


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