Abstract: The reception quality of an AM broadcast signal is determined within a very short time of tuning to the channel frequency by modifying the intermediate frequency signal to remove the audio information modulated on the carrier but including residual noise and higher frequencies. The modified IF signal is used to regenerate a pure sine-wave carrier as a replica of the original carrier wave at the transmitter. This pure carrier is compared to the modified IF signal to identify degradation during transmission.

Abstract: A radio receiver simultaneously achieves maximum sensitivity and minimum susceptibility to intermodulation distortion by employing wideband and narrowband automatic gain control which further selects the automatic gain control response in dependence on the detection of intermodulation distortion. An AGC signal is modified to improve sensitivity in the event of a low narrowband signal level except when intermodulation distortion is detected above a predetermined distortion level.

Abstract: A phase-locked loop is provided for operating in either a steady-state mode or a transient mode. The steady-state mode obtains high rejection of noise disturbances to maintain lock of the phase-locked loop. The transient mode provides a near deadbeat response in order to quickly acquire a new phase-locked loop frequency when a new frequency command is received.

Abstract: The radio receiver of the present invention detects the presence of adjacent channel interference in either the lower adjacent channel or the upper adjacent channel and shifts the received signals to remove the adjacent channel interference from the intermediate frequency passband, but only if the other adjacent channel is clear. A maximum amount of the desired signal is retained so that modulation distortion is low. Frequency limits for shifting of the desired signals prevent undesirable amounts of phase distortion from being introduced into the audio signal.

Abstract: Compounds that are analogs of etoposide and exhibit antitumor activity are disclosed. The compounds of the present invention have the following formula: ##STR1## where: R.sub.1 is .beta.-OCH.sub.2 CH.sub.2 NH.sub.2 .beta.-NHCH(CH.sub.3)CH.sub.2 OH, .beta.-NHCH.sub.2 CH(CH.sub.3)OH, .beta.-Cl, .beta.-Br, .beta.-OH, .alpha.-OH, .beta.-NH, .alpha.-NH.sub.2, .beta.-NHCH.sub.2 CH.sub.2 OH, .alpha.-NHCH.sub.2 CH.sub.2 OH, .beta.-NHCH.sub.2 CH.sub.2 CH.sub.3, .beta.-NHCH.sub.2 CH.sub.2 OCH.sub.3, .beta.-NHCH.sub.2 CH.dbd.CH.sub.2, .beta.-NHCH.sub.2 CH(OH)CH.sub.3, .beta.-NHCH.sub.2 CH.sub.2 CH.sub.2 OH, .beta.-OCH.sub.2 CH.sub.2 OH, ##STR2## R.sub.2 is H, or Br; R.sub.1 is H, or Br;R.sub.4 is H, or Br;R.sub.5 is H, or Br; andR.sub.6 is H, or --CH.sub.3.

Abstract: The reception of FM broadcast signals having a selected high sound quality is determined according to criteria including a low noise level and the absence of interference. The high quality information is employed to terminate a scan tuning operation or to activate an ultrasonic noise filter to improve listening quality of the FM audio output. The absence of noise and interference is determined by examining a particular frequency range from the FM field intensity line generated by an intermediate frequency circuit.