Table I
Ruby Laser Multipath Observations
| Date | Visibility | Pulse Characteristics | Weather Conditions |
|---|
|
|---|
| from Cambridge | from Waltham | type | duration | |
|---|
| 11/21/75 | 3 miles | 3 miles | i | 150 nsec | heavy rain |
| 2/18/76 | 1 mile | 0. 25 mile | – | – | heavy fog with light rain; unable to see any signal |
| 3/3/76 | 2 miles | 2 miles | i | 150 nsec | fog with light snow; signal faded out as visibility decreased to
mile at both terminals |
| 3/5/76 | | 5 miles | iii | 300-500 nsec | fog in Cambridge |
| 5/12/76 | 2-3 miles | 4 miles | iii | 200-400 nsec | fog with light rain |
| 6/1/76 | 6 miles | 6 miles | i | 150 nsec | light rain |
| 7/21/76 | 3-4 miles | 2-3 miles | i | 150 nsec | fog with light rain |
| 9/17/76 | 0. 5 mile | 0. 5 mile | – | – | fog and rain; unable to see any signal |
| 10/1/76 | 6 miles | 6 miles | i | 150 nsec | haze and fog |
| 10/6/76 | 3-4 miles | 2 miles | i | 150 nsec | fog |
| 10/8/76 | 6 miles | 6 miles | i | 150 nsec | haze |
| 10/20/76 | 6 miles | 2-3 miles | i | 150 nsec | fog and rain |
| 10/20/76 | 6 miles | 0. 5-1 mile | i | 150 nsec | heavy fog in Waltham |
| 11/5/76 | 3-4 miles | 0. 1-1 mile | ii | 150-200 nsec | fog in Waltham; at lowest visibility unable to see any signal, as fog lifted pulses had 150-200 nsec duration in 1 mile visibility |
| 11/10/76 | 7 miles | 5-6 miles | ii | 150 nsec | haze |
Table II
Ruby Laser Transmission Data
| Date | Visibility in Miles | Signal Voltage | Point No. |
|---|
|
|---|
| from Cambridge | from Waltham | Vmin | V | Vmax | vmin | v | vmax | |
|---|
| 10/1/76 | 6 | 6 | | 6 | | 250 | 460 | 800 | 1 |
| 10/6/76 | 3-4 | 2 | 2 | 3 | 4 | 0. 16 | 0. 40 | 0. 70 | 2 |
| 10/8/76 | 6-8 | 6-8 | 6 | 7 | 8 | 40 | 68 | 140 | 3 |
| 10/18/76 | 10-12 | 10-12 | 10 | 11 | 12 | 300 | 420 | 800 | 4 |
| 10/20/76 | 6 | 3 | 4 | 4.5 | 5 | 0.40 | 1.70 | 5.00 | 5 |
| 6 | 0.5-1 | 2.6 | 3. 3 | 4 | 2.00 | 3. 80 | 6. 00 | 6 |
| 10/22/76 | 10 | 10 | | 10 | | 200 | 600 | 1000 | 7 |
| 10/26/76 | 8 | 10 | 8 | 9 | 10 | 200 | 1410 | 2500 | 8 |
| 11/5/76 | 3-4 | 1-2 | 1 | 2 | 3 | 0.50 | 1. 25 | 2. 50 | 9 |
| 3-4 | 0. 1 | 1 | 1. 5 | 2 | . 07 | . 12 | . 22 | 10 |
| 11/10/76 | 7 | 5-6 | 5 | 6 | 7 | 75 | 130 | 200 | 11 |
These data were taken with coaxial transmitter-receiver alignment, 10 mRad transmitter beam divergence, and 20 mRad cone-angle receiver field of view. The minimum, nominal, and maximum visibilities, (V
min, V, and V
max, respectively) are ad hoc estimates of a homogeneous-path visibility that would produce the same unscattered-light extinction as the Cambridge-to-Waltham path. The signal voltages are based on storage oscilloscope observation of ten laser pulses, corrected for the Wratten filters employed prior to detection.
Table III
Holmium Laser Transmission Data
| Date | Visibility in Miles | Signal Voltage | Point No. |
|---|
|
|---|
| from Cambridge | from Waltham | Vmin | V | Vmax | vmin | v | vmax | |
|---|
| 8/26/76 | 8 | 8 | | 8 | | 3. 30 | 3. 95 | 4. 60 | 1 |
| 9/2/76 | 6 | 4-8 | 4 | 6 | 8 | 0. 70 | 0. 82 | 0. 950 | 2 |
| 8 | 4 | 4 | 6 | 8 | 1. 30 | 1. 50 | 1. 70 | 3 |
| 10/1/76 | 6 | 6 | | 6 | | 5. 20 | 7. 10 | 9. 00 | 4 |
| 10/4/76 | 15 | 15 | | 15 | | 7. 60 | 9. 30 | 11. 00 | 5 |
| 10/6/76 | 3-4 | 2 | 2 | 2. 7 | 3. 5 | 0. 12 | 0. 46 | 0. 80 | 6 |
| 10/18/76 | 10-12 | 10-12 | 10 | 11 | 12 | 2. 80 | 3. 40 | 4. 00 | 7 |
| 10/29/76 | 10 | 10 | | 10 | | 2. 40 | 2. 70 | 3. 00 | 8 |
| 11/5/76 | 3-4 | 2-3 | 2. 5 | 3 | 3. 5 | 0. 100 | 0. 112 | 0. 125 | 9 |
These data were taken with coaxial transmitter-receiver alignment, 5. 5 mRad transmitter beam divergence, and 20 mRad cone-angle receiver field of view. The minimum, nominal, and maximum visibilities (V
min, V, and V
max, respectively) are ad hoc estimates of a homogeneous-path visibility that would produce the same unscattered-light extinction as the Cambridge-to-Waltham path. The signal voltages, v
min and v
max, are the minimum and maximum levels (corrected for the Wratten filters) reached in 15 seconds of boxcar averaging with an effective time constant of 4 sec; v ≡ (v
min + v
max)/2.
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