Based off Astralbee's and Larry Alton Garrett's logic, I believe you may be referring to
Pivoting off of the prior two answers, my logic is as follows:
Taking the AM frequency 1480 as a raw number, we follow the instructions as below:
"DROP 5" = Subtract five: 1475
"ECHO 0" = Append a zero at the end: 14750
"NEGATE 0" = Invert the zero (as if it were a bit): 14751
"SPLIT 4" = Split at the number four: 1_4751 or 14_751
"ENTER 1" = Place a one in the gap: 114751 or 141751
Taking the sequence of numbers to stand for letters, there could be several groupings (I only list the ones that felt the most pertinent; there's bound to be several others that may be more revealing):
1. 114751 = 11 4 7 5 1 = K D G E A
or 2. 1 14 7 5 1 = A N G E A
3. 141751 = 14 17 5 1 = N Q E A
or 4. 14 1 7 5 1 = N A G E A
(Interesting that #2 and #4 are anagrams...)
Taking one of these sequences, we notice the word
AGN, which stands for "active galactic nucleus," an attribute to quasars
…and from your hints, we can make some reasonable assumptions, since
quasars are quite D-E-N-S-E, supermassive, and certainly "extraordinary" interstellar objects! Furthermore, you mention that this was from a radio frequency; quasars can be classified as radio-quiet or radio-loud, which might explain why it's a "strange message from space".
The parts where I'm unsure:
- I think you are asking for a specific type of quasar (or a named one, at least), given the extra letters "EA"; adding "S" (as per the second set of instructions) doesn't seem to clarify anything alphabetically or by value.
- Not sure if the fact it is an AM frequency (and not a FM frequency) has any difference; perhaps these are extra letters?
- Your hint, "No light", seems to contradict the idea that this is a quasar, since quasars can emit quite a lot of light (EM radiation).
- I'm also making an assumption on which sequence is a viable one, given I'm not quite sure of all the possible sequences available.