[BUG] Fairfield Experiments Archived Before February 2020 May have incorrect Response information.

[timronan]

Describe the bug
A user observed inconsistencies between a "2nd generation Fairfield 3C 5 Hz nodes running at 500 sps and with a pre-deployment gain of 18 dB" response that the NRL returns and this same response archived in YA 2020 PH5 experiments. We were informed that there was no complete NRL Fairfield response until February 2020.

PH5 experiments archived before February 2020 may not have complete Fairfield responses, and therefore, the responses of these experiments could be inaccurate.

We should investigate a pre-Febrarury 2020 PH5 Fairfield experiment to determine if the archived response information is satisfactory or if these responses need to be updated.

response = nrl.get_response( # doctest: +SKIP
    sensor_keys=['Magseis Fairfield', 'Generation 2', '5 Hz'],
    datalogger_keys=['Magseis Fairfield', 'Zland 1C or 3C', '18 dB (8)', '500', 'Linear Phase', 'Off'])

Figure 1: Bode plot from the NRL.

Figure 2: Bode plot for the YA 2020 experiment.