(Revised September 1980) CCWN 77:106 period gives Morse of 1.2 words/minute, and a theoretical improvement of 34 dB. A 10-second integration period gives Morse of 0,12 words/minute and about 44 dB improvement. These speeds may seem a bit slow, but the improvement in effective communication with lower power is quite fascinating. In practice, the improvement gained by long-frame ccw is limited by phase modulation introduced by the propagation path. For 14 MHz signals, phase modulation due to the F layer's motion produces 2 or 3 Hz of phase (or frequency) modulation for a JA-W6 14 MHz wave. [We have also observed what appears to be propagation time delays under poor band condi- tions.] When the filter becomes so narrow that this modulation exceeds the filter bandwidth, then further improvement in signal-to-noise ratio cannot be obtained by narrowing the filter. In evaluating filter effectiveness, noise band width does not tell the whole story; there are psychological considerations, too. The human ear is frequency sensitive, and the human brain can focus on particular frequencies of cw signals among the noise and QRM. Skillful cw opera- tors can use this capability better. My observations have let me to conclude that this is worth at least 6 dB when using a 2300 Hz filter; however, QRM is often confusing and therefore causes more degradation of copy than an equivalent amount of random noise. These psycho- logical factors are difficult to quantify but probably reduce the advantage of ccw over ordinary cw. Figure 6 shows graphically the results of on-the-air comparison made in 1975 between ccw and cw. Transmissions were made on 14,049,000 Hz from JR1ZZR at 10 watts, 1 watt, and 0.1 watt using ccw and a vertical ground plane antenna on a four-story building. Reception was by a three-element beam at W61313. The ccw signals were received simultaneously as cw and ccw signals and recorded on separate channels of a stereo cassette recorder. We selected sample periods from the cassette recording, and played the cw and ccw chan- nels of the cassette back to four moderately experienced cw operators. The average proportion of copy shown on the graphs is based upon word count with recognizable words considered copied. The content was from radio journals. Extrapolation of these data indicate an estimate of 13 watts cw as equivalent to 0.1 watt ccw in communication effectiveness, or 24 dB superiority for ccw. In conclusion, I judge 0.1 second ccw to be over 20 dB better than cw with 500 Hz analog filter for moderately strong signals, and about 30 dB better than cw with-a 500 Hz analog filter for weak and very weak signals. Skillful operators can probably reduce these differences by a few dI3. Concluding Remarks "Knowing what you're looking for" does indeed help when receiving cw signals, the ccw technique appears most promising, especially where signals are weak compared to the noise and QRM. Under conditions of high absorption and QRN, as is often experienced on 80 and 160 meters, the additional selectivity of ccw would be very helpful. We don't have data on that yet. ccw might also be applied to EME communication, but there, the problem is more difficult because of Doppler effects due to lunar motion, one might need a computer to calcu- late on-line the frequency at which the signal is expected to return. Also, achieving the neces- sary frequency stability of a Hz or two is more difficult at the vhf and uhf frequencies used for EME. A word about receiver quality is in order. Some of the simplest rigs are the easiest to convert for ccw operation. However, to get the full advantage of the ccw mode, receivers must be of as high a quality as possible. The receiver properties of sensitivity, selectivity, stability, resetability, oscillator purity, dynamic range, and resistance to cross-modulation are all being pushed to the limits in the operation described here. Next month, in part two of this article, I will describe practical methods and equipment for communicating by ccw.