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RADIOTELEMETRY FIELD STUDIES <br />BACKGROUND <br />Sinning (1979) compiled information from several radiotelemetry fish <br />tracking studies done 1n waters of conductivities of 600 umho's or less <br />(Table 3). Some studies were not referenced in Table 3 because results were <br />similar to those referenced or the publications reporting on the study were <br />not readily available. At least partial success was reported For all of the <br />studies referenced in Table 3. The highest reported water conductivity was <br />600 umho, with a useable signal depth of about 2 m. No signal could be <br />detected at 6 m in water of this conductivity. Most of the transmitters used <br />in the studies were homemade with widely variab]e design characteristics. <br />Receivers varied from sophisticated communications equipment to converted <br />inexpensive transistor radios. For most of the studies, receiving antenna <br />types and specifications were not reported. The type of receiving antenna can <br />make a major difference in the range at which transmissions can be received. <br />Table 3 also presents some conditions affecting reception at different <br />ranges. Conditions which could affect range but are not listed include antenna <br />type, water surface character (e.g., wave action), antenna height, transmitter <br />output power, transmitter antenna type, receiving antenna gain, transmission <br />line losses, receiver noise, and presence and strength of interfering signals. <br />Results of radiotelemetry studies listed in Table 3 were evaluated by <br />Sinning (1979) and analyzed by linear regression. Results of the regression <br />analysis were essentially inconclusive, probably due to variation in the <br />equipment used in the studies. However, when data from Larimore et al. (1975) <br />were analyzed, the regression of the log of the depth versus the range was <br />significant at P <_ 0.5 (r = 0.998, n = 3) for 600 umho conductivity. This <br />simply implies that the range decreases as the depth increases. A manual <br />published by the AVM Instrument company (1979) includes ranges for their 49 to <br />50 MHz fish modu]es at 600 pmho conductivity, which seem to correlate with <br />range and depth relationships discussed by Sinning (1979). <br />Although attempts have been made to predict the range of radiotelemetry <br />at given depths and conductivity values, a predictive model for practical <br />application has not been developed. It fs uncertain if a model could be <br />developed for practical use since environmental variables and different radio <br />transmitting and receiving systems introduce large error terms. Even if pre- <br />dictive models could be developed, they may have limited utility because <br />researchers often have to experiment with equipment to attain satisfactory <br />results in different environments. <br /> <br /> <br />~~ <br />Ed» E <br />E <br />E <br />E ~d <br />Ed <br /> °~ <br /> <br />6 y.. d <br />C d <br />d~N d O~ d <br /> <br />r d <br /> <br />r d <br /> <br />4 d <br />a+9 <br />ra <br />d <br /> <br /> <br /> <br />d <br /> <br />~~ <br /> <br /> <br />N <br /> <br /> <br /> <br />-. L omw <br />t"d <br />.a <br />.+yPy <br />f N 1 O~Y <br />Y <br />~ <br />n <br />~ <br />O L <br />M L W ~ y <br />W <br /> L L fY <br /> " v <br />~ i' o <br />' S.~ ~ <br />' <br />~ <br />~ <br />N 'mo <br />s s a.- o-+ ~ <br />a ~ <br />a °° <br />s eogs~.u, <br />i~'c nri <br />L <br />"- <br />A <br />~.. ao ~ A ~ ,, g a ` a <br />e <br />N <br />w <br />:o <br />rn <br />c <br /> <br />.. <br /> <br />~ <br /> <br />~ <br /> <br />"> <br /> <br />.~ <br />~ <br />'b <br />c <br />v <br /> <br />~ w <br /> <br />zcv <br />° <br />om <br /> <br />u+ao <br />n~ ~o a~~ <br /> <br /> <br /> <br />~o <br />> <br /> <br /> <br />~ s <br />o.o <br />.o <br />ga <br />o~ <br /> <br />m <br /> <br />o <br />s <br />v- <br />O <br />a, <br />+' <br /> <br />c <br /> <br />c <br />E <br />EE <br />N <br /> <br />M <br /> <br />a goo <br />u.., <br /> <br />r <br />y w <br /> <br />ev a u~i" a <br />w u <br /> <br /> <br /> <br /> <br />e `~~'~ <br />m <br /> <br /> <br />0 c <br />gw v~ <br /> <br /> <br /> <br />0 <br /> L O O <br /> <br /> <br />o <br /> <br />0 <br />d <br />d <br /> <br /> <br />~~ <br /> i w <br />.q z ~ <br />.~ <br /> Cp <br /> <br />w P G' <br />_ ~ u <br />~ <br />~ ~ ° ~ <br />~, <br />O 6' ~ <br />tl' <br />A <br />c~ +du" <br />g ?. M <br /> <br />Y N <br />°~~ <br />L <br /> ~ o <br />~ E a C <br />z0 v~b d <br />~ oc <br />au¢ <br />12 ~ '13 <br />